Prematurity

Prematurity also called preterm or “preemie”, is a term for the broad category of babies born at less than 37 weeks’ gestation ¹⁾. Preterm birth is when a baby is born too early, before 37 weeks of pregnancy have been completed ²⁾. So a baby born at 36 weeks and 6 days is officially premature. A baby born before the 37th week is known as a premature or pre-term baby. Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization ³⁾. Many premature babies also weigh less than 2,500 grams (5 lbs. 8 oz.) and may be referred to as low birthweight (LBW). For premature infants born with a weight below 1000 g, the three primary causes of mortality are respiratory failure, infection, and congenital malformation.

Normal pregnancy usually lasts an average of 40 weeks (normally between 38 and 42 weeks).

The degree of prematurity is often described by gestational age as:

• Extremely premature: from 23-28 weeks
• Very premature: 28-32 weeks
• Moderately premature: 32-34 weeks
• Late preterm (near-term): 34-37 weeks.
  • Late preterm infants are often much larger than very premature infants but may only be slightly smaller than full-term infants. Late preterm babies usually appear healthy at birth but may have more difficulties adapting than full-term babies. Because of their smaller size, they may have trouble maintaining their body temperature. They often have difficulty with breastfeeding and bottle feeding, and may need to eat more frequently. They usually require more sleep and may even sleep through a feeding, which means they miss much-needed calories. Late preterm infants may also have breathing difficulties, although these are often identified before the infants go home from the hospital. These infants are also at higher risk for infections and jaundice, and should be watched for signs of these conditions. Late preterm infants should be seen by a care provider within the first one or two days after going home from the hospital.

Premature infants are also categorized by birthweight:

• < 1000 g: Extremely low birthweight (ELBW)
• 1000 to 1499 g: Very low birthweight (VLBW)
• 1500 to 2500 g: Low birthweight (LBW)

Babies born too early (especially before 32 weeks) have higher rates of death and disability. In 2017, preterm birth and low birth weight accounted for about 17% of infant deaths ⁴⁾. Babies who survive may have:

• Breathing problems
• Feeding difficulties
• Cerebral palsy
• Developmental delay
• Vision problems
• Hearing problems

Preterm births may also take an emotional toll and be a financial burden for families.

Slightly fewer than 12 percent of all babies are premature. Overall, the rate of premature births is rising, mainly due to the large numbers of multiple births in recent years. Twins and other multiples are about six times more likely to be premature than single birth babies. The rate of premature single births is also slightly increasing each year.

In 2018, preterm birth affected 1 of every 10 infants born in the United States and the rate of preterm birth among African-American women (14%) was about 50 percent higher than the rate of preterm birth among white women (9%) ⁵⁾.

According to the National Center for Health Statistics for 2011, 12 percent of babies born in the U.S. are born preterm, or before 37 completed weeks of pregnancy. Of all babies:

• About 8 percent are born between 34 and 36 weeks of gestation (the time from conception to birth)
• About 1.5 percent are born between 32 and 33 weeks of gestation
• About 2 percent are born under 32 weeks of gestation

More than 90% of these premature babies survive. And survival rates keep getting better as medical knowledge gets better.

Survival is affected by how premature a baby is. For example, moderately preterm babies are more likely to survive than extremely preterm babies. Babies born after only 23 weeks have a reasonable chance of survival – more than 50%.

The majority of preterm children develop normally. The longer your baby’s gestation, the less chance there is of any health or developmental concerns.

Babies who are born late preterm generally have no serious long-term problems.

Extremely premature babies (born at 28 weeks or less) have an increased risk of developmental problems. But even in extremely premature babies, severe developmental problems are still quite uncommon.

Key points about prematurity:

• Babies born before 37 weeks of pregnancy are considered premature or born too early.
• Many premature babies also weigh less than 5 pounds, 8 ounces (2,500 grams). They may be called low birth weight.
• Premature babies can have long-term health problems. In general, the more premature the baby, the more serious and long-lasting the health problems may be.
• Prenatal care is a key factor in preventing preterm births and low-birth-weight babies.
• Premature babies are at increased risk for sudden infant death syndrome (SIDS).
• Even though they are otherwise ready for discharge, some premature babies still need special care when they go home.

What are the characteristics of prematurity?

The following are the most common characteristics of a premature baby. However, each baby may show different characteristics of the condition. Characteristics may include:

• Small baby, often weighing less than 2,500 grams (5 lbs. 8 oz.)
• Thin, shiny, pink or red skin, able to see veins
• Little body fat
• Little scalp hair, but may have lots of lanugo (soft body hair)
• Weak cry and body tone
• Genitals may be small and underdeveloped

The characteristics of prematurity may resemble other conditions or medical problems. Always consult your baby’s doctor for a diagnosis.

Why is prematurity a concern?

Premature babies are born before their bodies and organ systems have completely matured. These babies are often small, with low birthweight (less than 2,500 grams or 5 lbs. 8 oz.), and they may need help breathing, eating, fighting infection, and staying warm. Very premature babies, those born before 28 weeks, are especially vulnerable. Many of their organs may not be ready for life outside the mother’s uterus and may be too immature to function well.

Some of the problems premature babies may experience include:

• Temperature instability–inability to stay warm due to low body fat.
• Respiratory problems:
  • Infant respiratory distress syndrome (previously called hyaline membrane disease). A condition in which the air sacs cannot stay open due to lack of surfactant in the lungs.
  • Chronic lung disease/bronchopulmonary dysplasia. These are long-term respiratory problems caused by injury to the lung tissue.
  • Air leaking out of the normal lung spaces into other tissues
  • Incomplete lung development
  • Apnea (stopping breathing). This occurs in about half of babies born at or before 30 weeks.
• Cardiovascular:
  • Patent ductus arteriosus (PDA). A heart condition that causes blood to divert away from the lungs.
  • Too low or too high blood pressure
  • Low heart rate. This often occurs with apnea.
• Blood and metabolic:
  • Anemia. This may require blood transfusion.
  • Jaundice. This is due to immaturity of liver and gastrointestinal function.
  • Too low or too high levels of minerals and other substances in the blood, such as calcium and glucose (sugar)
  • Immature kidney function
• Gastrointestinal:
  • Difficulty feeding. Many premature babies are unable to coordinate suck and swallow before 35 weeks gestation.
  • Poor digestion
  • Necrotizing enterocolitis (NEC). A serious disease of the intestine common in premature babies.
• Neurologic:
  • Intraventricular hemorrhage. This is bleeding in the brain.
  • Periventricular leukomalacia. A softening of tissues of the brain around the ventricles (the spaces in the brain containing cerebrospinal fluid).
  • Poor muscle tone
  • Seizures. These may be due to bleeding in the brain.
  • Retinopathy of prematurity. This is abnormal growth of the blood vessels in a baby’s eye.
• Infections. Premature infants are more susceptible to infection and may require antibiotics.

Premature babies can have long-term health problems as well. Generally, the more premature the baby, the more serious and long-lasting are the health problems.

What causes prematurity?

There are many factors linked to premature birth. Some directly cause early labor and birth, while others can make the mother or baby sick and require early delivery. The following factors may contribute to a premature birth:

• Maternal factors
  • Preeclampsia (high blood pressure of pregnancy, also known as toxemia or gestational hypertension)
  • Chronic medical illness (such as heart or kidney disease)
  • Infection (such as group B streptococcus, urinary tract infections, vaginal infections, infections of the fetal/placental tissues)
  • Drug use (such as cocaine)
  • Abnormal structure of the uterus
  • Cervical incompetence (inability of the cervix to stay closed during pregnancy)
  • Previous preterm birth
• Factors involving the pregnancy
  • Abnormal or decreased function of the placenta
  • Placenta previa (low lying position of the placenta)
  • Placental abruption (early detachment from the uterus)
  • Premature rupture of membranes (amniotic sac)
  • Polyhydramnios (too much amniotic fluid)
• Factors involving the fetus
  • When fetal behavior indicates the intrauterine environment is not healthy
  • Multiple gestation (twins, triplets or more).

Who is at risk for prematurity?

Many women have no known risk factors for premature birth. But several things can make premature birth more likely.

Women with these risk factors are more likely to deliver early:

• Having had a previous preterm labor or birth
• Getting pregnant within a short time (less than a year) after having had a baby
• Carrying twins, triplets, or more babies at one time
• Having an abnormal cervix or uterus
• Being younger than 16 or older than 35
• Being African American
• Having long-term health problems such as heart disease or kidney disease
• Smoking
• Using illegal drugs such as cocaine

In addition, women who develop any of the following problems during pregnancy are more likely to deliver early:

• Infections
• High blood pressure
• Diabetes
• Blood-clotting problems
• Problems with the placenta
• Vaginal bleeding

Certain developmental problems can put unborn babies at higher risk for prematurity.

What are the risk factors for a preterm birth?

Many times doctors do not know what causes a woman to deliver early, but several known factors may increase the likelihood that a woman could deliver early.

Social, personal, and economic characteristics:

• Teens and women over age 35
• Black race
• Women with low income

Pregnancy and medical conditions:

• Prior preterm birth
• Infection
• Carrying more than 1 baby (twins, triplets, or more)

Behavioral factors:

• Tobacco use
• Substance use
• Stress.

Can anything be done to prevent a preterm birth?

Preventing preterm birth remains a challenge because there are many causes of preterm birth and because causes may be complex and not always well understood. However, pregnant women can take important steps to help reduce their risk of preterm birth and improve their general health.

Here are some steps to reduce your risk of having a preterm birth:

• Quit smoking.
• Avoid alcohol and drugs.
• Get prenatal care as soon as you think you may be pregnant and throughout the pregnancy.
• Seek medical attention for any warning signs or symptoms of preterm labor.
• Talk with your doctor or other healthcare provider about the use of progesterone treatment if you had a previous preterm birth. Your healthcare provider may give you the hormone progesterone if you are at high risk for preterm birth. Progesterone can help if you have had a previous preterm birth.

Another step women and their partners can take to reduce the risk of preterm birth is waiting at least 18 months between pregnancies.

Prenatal care is a key factor in preventing preterm births and low birthweight babies. At prenatal visits, the health of both mother and fetus can be checked. Because maternal nutrition and weight gain are linked with fetal weight gain and birthweight, eating a healthy diet and gaining weight in pregnancy are essential. Prenatal care is also important in identifying problems and lifestyles that can increase the risks for preterm labor and birth. Some ways to help prevent prematurity and to provide the best care for premature babies may include the following:

• Identifying mothers at risk for preterm labor
• Prenatal education of the symptoms of preterm labor
• Avoiding heavy or repetitive work or standing for long periods of time that can increase the risk of preterm labor
• Early identification and treatment of preterm labor

Does using in-vitro fertilization (IVF) or assisted reproductive treatment (ART) increase my risk of having a preterm birth?

Women who conceive through ART are at higher risk for preterm birth, primarily because they are more likely to be pregnant with more than one baby at a time ⁶⁾.

What are the warning signs and symptoms of preterm labor?

In most cases, preterm labor (labor that happens too soon, before 37 weeks of pregnancy) begins unexpectedly and the cause is unknown.

If you have any of the following symptoms, you should contact your health professional – that is, your midwife, doctor or hospital. These symptoms might or might not mean you’re in labor, but you should always have them checked out.

It might be that you just don’t feel right, even though you don’t have any particular symptoms. If this happens, trust your own instincts. See your doctor or go to the hospital.

Like regular labor, signs of early labor (preterm labor) are:

• Contractions (the abdomen tightens like a fist) every 10 minutes or more often
• Change in vaginal discharge (a significant increase in the amount of discharge or leaking fluid or bleeding from the vagina)
• Pelvic pressure—a feeling that your baby is pushing down or a feeling of pressure in your pelvis
• Low, dull backache
• Cramps that feel like a menstrual period
• Abdominal cramps with or without diarrhea
• Swelling in your hands, feet or face
• Nausea, vomiting or diarrhea
• Blurriness, double vision or other eye disturbances
• Abdominal cramps, much like period pain
• Your baby’s movements slowing down or stopping

If you think you are experiencing premature labor, it is important that you see a healthcare provider right away. If you are less than 37 weeks pregnant and you experience any of the signs of premature labor (preterm labor), such as contractions, your waters breaking, bleeding, a ‘show’ of mucus from your vagina or a sudden decrease in your baby’s movements, contact your doctor or nearest delivery suite immediately. It may be possible to slow down or stop the labor and your doctor may be able to give you medicine so that the baby will be healthier at birth. But each day the baby stays inside your womb, the greater their chance of survival.

What are the symptoms of prematurity?

Each baby may show slightly different symptoms. The following are the most common symptoms of a premature baby:

• Small size. Premature babies often weigh less than 5 pounds, 8 ounces.
• Thin, shiny, pink, or red skin. You may be able to see veins through the skin.
• Little body fat
• Little scalp hair. But the baby may have lots of soft body hair (lanugo)
• Weak cry
• Low muscle tone
• Male and female genitals are small and not yet fully developed

The symptoms of prematurity may look like other health conditions. Make sure your child sees his or her healthcare provider for a diagnosis.

What are the complications of prematurity?

Premature babies are cared for by a neonatologist. This is a doctor with special training to care for newborns. Other specialists may also care for babies, depending on their health problems.

Premature babies are born before their bodies and organ systems have completely matured. These babies are smaller than they would have been if they were born at full term. They may need help breathing, eating, fighting infection, and staying warm. Extremely premature babies, those born before 28 weeks, are at the greatest risk for problems. Their organs and body systems may not be ready for life outside the mother’s uterus. And they may be too immature to function well.

Some of the problems premature babies may have include:

• Keeping their body temperature steady or staying warm
• Breathing problems, including serious short- and long-term problems
• Blood problems. These include low red blood cell counts (anemia), yellow-color to the skin from breaking down old red blood cells (jaundice), or low blood sugar levels (hypoglycemia).
• Kidney problems
• Digestive problems, including trouble feeding and poor digestion. In some cases there may be inflammation and death of parts of the intestine (necrotizing enterocolititis).
• Nervous system problems, including bleeding in the brain or seizures
• Infections

Premature babies can have long-term health problems as well. Generally, the more premature the baby, the more serious and long-lasting the health problems may be.

Cardiac

The overall incidence of structural congenital heart defects among premature infants is low. The most common cardiac complication is:

• Patent ductus arteriosus (PDA): The ductus arteriosus is more likely to fail to close after birth in premature infants. The incidence of patent ductus arteriosus increases with increasing prematurity; patent ductus arteriosus occurs in almost half of infants whose birthweight is < 1750 g and in about 80% of those < 1000 g. About one third to one half of infants with patent ductus arteriosus have some degree of heart failure. Premature infants ≤ 29 weeks gestation at birth who have respiratory distress syndrome have a 65 to 88% risk of a symptomatic PDA. If infants are ≥ 30 weeks gestation at birth, the ductus closes spontaneously in 98% by the time of hospital discharge.

Central nervous system (CNS)

Central nervous system complications include:

• Poor sucking and swallowing reflexes: Infants born before 34 weeks gestation have inadequate coordination of sucking and swallowing reflexes and need to be fed intravenously or by gavage.
• Apneic episodes: Immaturity of the respiratory center in the brain stem results in apneic spells (central apnea). Apnea may also result from hypopharyngeal obstruction alone (obstructive apnea). Both may be present (mixed apnea).
• Intraventricular hemorrhage: The periventricular germinal matrix (a highly cellular mass of embryonic cells that lies over the caudate nucleus on the lateral wall of the lateral ventricles of a fetus) is prone to hemorrhage, which may extend into the cerebral ventricles (intraventricular hemorrhage). Infarction of the periventricular white matter (periventricular leukomalacia) may also occur for reasons that are incompletely understood. Hypotension, inadequate or unstable brain perfusion, and blood pressure peaks (as when fluid or colloid is given rapidly IV) may contribute to cerebral infarction or hemorrhage. Periventricular white matter injury is a major risk factor for cerebral palsy and neurodevelopmental delays.
• Developmental and/or cognitive delays: Premature infants, particularly those with a history of sepsis, necrotizing enterocolitis, hypoxia, and intraventricular and/or periventricular hemorrhages, are at risk of developmental and cognitive delays (see also Childhood Development). These infants require careful follow-up during the first year of life to identify auditory, visual, and neurodevelopmental delays. Careful attention must be paid to developmental milestones, muscle tone, language skills, and growth (weight, length, and head circumference). Infants with identified delays in visual skills should be referred to a pediatric ophthalmologist. Infants with auditory and neurodevelopmental delays (including increased muscle tone and abnormal protective reflexes) should be referred to early intervention programs that provide physical, occupational, and speech therapy. Infants with severe neurodevelopmental problems may need to be referred to a pediatric neurologist.

Eyes

Ocular complications include:

• Retinopathy of prematurity (ROP): Retinal vascularization is not complete until near term. Preterm delivery may interfere with the normal vascularization process, resulting in abnormal vessel development and sometimes defects in vision including blindness (ROP). Incidence of ROP is inversely proportional to gestational age. Disease usually manifests between 32 weeks and 34 weeks gestational age.
• Myopia and/or strabismus:Incidence of myopia and strabismus increases independently of ROP.

Gastrointestinal tract

Gastrointestinal complications include:

• Feeding intolerance, with increased risk of aspiration: Feeding intolerance is extremely common because premature infants have a small stomach, immature sucking and swallowing reflexes, and inadequate gastric and intestinal motility. These factors hinder the ability to tolerate both oral and nasogastric feedings and create a risk of aspiration. Feeding tolerance increases over time, particularly when infants are able to be given some enteral feedings.
• Necrotizing enterocolitis: Necrotizing enterocolitis usually manifests with bloody stool, feeding intolerance, and a distended, tender abdomen. Necrotizing enterocolitis is the most common surgical emergency in the premature infant. Complications of neonatal necrotizing enterocolitis include bowel perforation with pneumoperitoneum, intra-abdominal abscess formation, stricture formation, short bowel syndrome, septicemia, and death.

Infection

Infectious complications include:

• Sepsis
• Meningitis

Sepsis or meningitis is about 4 times more likely in the premature infant, occurring in almost 25% of very low-birthweight infants. The increased likelihood results from indwelling intravascular catheters and endotracheal tubes, areas of skin breakdown, and markedly reduced serum immunoglobulin levels.

Kidneys

Renal complications include:

• Metabolic acidosis
• Growth failure

Renal function is limited, so the concentrating and diluting limits of urine are decreased. Late metabolic acidosis and growth failure may result from the immature kidneys’ inability to excrete fixed acids, which accumulate with high-protein formula feedings and as a result of bone growth. Sodium and bicarbonate are lost in the urine.

Lungs

Pulmonary complications include:

• Respiratory distress syndrome (RDS)
• Respiratory insufficiency of prematurity
• Chronic lung disease (bronchopulmonary dysplasia)

Surfactant production is often inadequate to prevent alveolar collapse and atelectasis, which result in respiratory distress syndrome (hyaline membrane disease). Many other factors can contribute to respiratory distress in the first week of life. Regardless of the cause, many extremely premature and very premature infants have persistent respiratory distress and an ongoing need for respiratory support (termed Wilson-Mikity disease, chronic pulmonary insufficiency of prematurity, or respiratory insufficiency of prematurity). Some infants are successfully weaned off support over a few weeks; others develop chronic lung disease (bronchopulmonary dysplasia) with need for prolonged respiratory support using a high-flow nasal cannula, continuous positive airway pressure (CPAP) or other noninvasive ventilatory assistance, or mechanical ventilation. Respiratory support may be given with room air or with supplemental oxygen. If supplemental oxygen is required, the lowest oxygen concentration that can maintain target oxygen saturation levels of 90 to 95% should be used.

Palivizumab prophylaxis for respiratory syncytial virus is important for infants with chronic lung disease.

Metabolic problems

Metabolic complications include:

• Neonatal hypoglycemia and neonatal hyperglycemia
• Hyperbilirubinemia: Hyperbilirubinemia occurs more commonly in the premature as compared to the term infant, and kernicterus (brain damage caused by hyperbilirubinemia) may occur at serum bilirubin levels as low as 10 mg/dL (170 micromol/L) in small, sick, premature infants. The higher bilirubin levels may be partially due to inadequately developed hepatic excretion mechanisms, including deficiencies in the uptake of bilirubin from the serum, its hepatic conjugation to bilirubin diglucuronide, and its excretion into the biliary tree. Decreased intestinal motility enables more bilirubin diglucuronide to be deconjugated within the intestinal lumen by the luminal enzyme beta-glucuronidase, thus permitting increased reabsorption of unconjugated bilirubin (enterohepatic circulation of bilirubin). Conversely, early feedings increase intestinal motility and reduce bilirubin reabsorption and can thereby significantly decrease the incidence and severity of physiologic jaundice. Uncommonly, delayed clamping of the umbilical cord (which has several benefits and is generally recommended) may increase the risk of hyperbilirubinemia by allowing the transfusion of red blood cells (RBCs) thus increasing red blood cell breakdown and bilirubin production.
• Metabolic bone disease (osteopenia of prematurity): Metabolic bone disease with osteopenia is common, particularly in extremely premature infants. It is caused by inadequate intake of calcium, phosphorus, and vitamin D and is exacerbated by administration of diuretics and corticosteroids. Breast milk also has insufficient calcium and phosphorus and must be fortified. Supplemental vitamin D is necessary to optimize intestinal absorption of calcium and control urinary excretion.
• Congenital hypothyroidism: Congenital hypothyroidism, characterized by low thyroxine (T4) and elevated thyroid-stimulating hormone (TSH) levels, is much more common among premature infants than full-term infants. In infants with a birthweight of < 1500 g, the rise in TSH may be delayed for several weeks, necessitating repeated screening for detection. Transient hypothyroxinemia, characterized by low T4 and normal TSH levels, is very common among extremely premature infants; treatment with L-thyroxine is not beneficial ⁷⁾.

Temperature regulation

The most common temperature regulation complication is:

• Hypothermia: Premature infants have an exceptionally large body surface area to volume ratio. Therefore, when exposed to temperatures below the neutral thermal environment, they rapidly lose heat and have difficulty maintaining body temperature. The neutral thermal environment is the environmental temperature at which metabolic demands (and thus calorie expenditure) to maintain normal body temperature (36.5 to 37.5° C rectal) are lowest.

How is prematurity diagnosed?

A baby born before 37 weeks of pregnancy is considered premature or born too early. Prematurity is defined as:

• Early term infants. Babies born between 37 weeks and 38 weeks, 6 days.
• Late preterm infants. Babies born between 34 weeks and 36 weeks, 6 days.
• Very preterm. Babies born at or below 32 weeks.
• Extremely preterm. Babies born at or below 28 weeks.

What is the treatment for premature birth?

Most preterm babies arrive early without warning. If a pregnancy is found to be at high risk of premature birth, the mother is treated to extend the pregnancy as far as possible. There are various ways this is done. Preventing preterm birth is important because it gives your baby more time to develop in the womb so that they are fully ready for life outside the womb.

Specific treatment for prematurity will be determined by your baby’s doctor based on:

• Your baby’s gestational age, overall health, and medical history
• Extent of the disease
• Tolerance for specific medications, procedures, or therapies
• Expectations for the course of the disease
• Your opinion or preference

Treatment may include:

• Prenatal corticosteroid therapy. One of the most important parts of care for premature babies is a medication called corticosteroids. Research has found that giving the mother a steroid medication at least 48 hours prior to preterm delivery greatly reduces the incidence and severity of respiratory disease in the baby. Another major benefit of steroid treatment is lessening of intraventricular hemorrhage (bleeding in the baby’s brain). Although studies are not clear, prenatal steroids may also help reduce the incidence of NEC and PDA. Mothers may be given steroids when preterm birth is likely between 24 and 34 weeks of pregnancy. Before that time, or after, the medication usually is not effective.
• Premature babies usually need care in a special nursery called the Neonatal Intensive Care Unit (NICU). The NICU combines advanced technology and trained health professionals to provide specialized care for the tiniest patients. The NICU team is led by a neonatologist, who is a pediatrician with additional training in the care of sick and premature babies.

Care of premature babies may also include:

• Temperature-controlled beds
• Monitoring of temperature, blood pressure, heart and breathing rates, and oxygen levels
• Giving extra oxygen by a mask or with a breathing machine
• Mechanical ventilators (breathing machines) to do the work of breathing for the baby
• Intravenous (IV) fluids, when feedings cannot be given, or for medications
• Placement of catheters (small tube) into the umbilical cord to give fluids and medications and to draw blood
• X-rays (for diagnosing problems and checking tube placement)
• Special feedings of breast milk or formula, sometimes with a tube into the stomach if a baby cannot suck. Breast milk has many advantages for premature babies as it contains immunities from the mother and many important nutrients.
• Medications and other treatments for complications, such as antibiotics
• Kangaroo Care. A method of caring for premature babies using skin-to-skin contact with the parent to provide contact and aid parent-infant attachment. Studies have found that babies who “kangaroo” may have shorter stays in the NICU.

What is a premature baby?

A premature baby is one who is born too early, before 37 weeks of pregnancy. Each year, about 1 in 10 babies in the United States is born prematurely. Premature babies may not be fully developed at birth. They may have more health problems and may need to stay in the hospital longer than babies born later. Thanks to advances in medical care, even babies born very prematurely are more likely to survive today than ever before.

Your baby’s health care provider may use these terms to describe your baby’s birth:

• Late preterm: Your baby is born between 34 and 36 completed weeks of pregnancy.
• Moderately preterm: Your baby is born between 32 and 34 weeks of pregnancy.
• Very preterm: Your baby is born at less than 32 weeks of pregnancy.
• Extremely preterm: Your baby is born at or before 25 weeks of pregnancy.

Some health problems related to premature birth can last a lifetime. Other problems, like intellectual or developmental disabilities, can show up as your baby grows and later in childhood. These are problems with how the brain works that can cause a person to have trouble or delays in physical development, learning, communicating, taking care of himself or getting along with others.

The earlier in pregnancy a baby is born, the more likely he/she is to have health problems. Babies born before 34 weeks of pregnancy are mostly likely to have health problems, but babies born between 34 and 37 weeks of pregnancy are also at increased risk of having health problems related to premature birth. Some premature babies need to spend time in a hospital’s newborn intensive care unit also called NICU. This is the nursery in a hospital where sick newborns get medical care. Premature babies stay in the neonatal intensive care unit (NICU) until their organs develop enough to stay alive without medical support. Some babies need NICU care for weeks or months until they can breathe on their own, eat by mouth and maintain their body temperature and body weight.

Premature baby key points:

• Premature babies may have more health problems than babies born later. These include problems with their brain, lungs, heart, eyes and other organs.
• Some premature babies have to spend time in a hospital’s newborn intensive care unit (NICU) to get special medical care.
• Premature birth can lead to long-term challenges for some babies, including intellectual and developmental disabilities.
• After they leave the hospital, premature babies get regular checkups to monitor their health and development.
• If you’re worried about your baby’s health or development at any time, tell your baby’s doctor right away.

What is my baby’s gestational age?

Gestational age is the length of time your baby has been developing in your uterus. It’s calculated from the first day of your last menstrual period (LMP). However, gestational age dating using the mother’s history can be unreliable because of uncertainty of the dates. About 20% of women have an uncertain last menstrual period.

Exact gestational age is important because the more premature babies are, the less developed they will be. And this means that they’ll probably need more medical support for their lungs, hearts, tummy and bowels, temperature control and feeding.

For example, most babies who are born at less than 32 weeks of pregnancy will need help with breathing. This means they’ll be cared for in a neonatal intensive care unit (NICU). If they’re more developed, they might be cared for in a special care nursery (SCN).

Confirming your baby’s gestational age

Gestational age assessment begins prenatally with obstetric ultrasonography in the first trimester. Discovery of many fetal anomalies, unsuspected multiple gestation, location of the placenta, and an accurate dating of the pregnancy are additional major benefits of early ultrasonography.

The Ballard Scoring System remains the main tool clinicians use after delivery to confirm gestational age by means of physical examination ⁸⁾. The major parts of the anatomy used in determining gestational age include the following:

• Ear cartilage (eg, a preterm infant at 28 weeks’ gestation has a small amount of ear cartilage and/or a flattened pinna)
• Sole (eg, a preterm infant at 33 weeks’ gestation has only an anterior crease on the sole of the foot)
• Breast tissue (eg, a preterm infant at 28 weeks’ gestation has no breast tissue, and the areolae are barely visible)
• Genitalia

Neurologic criteria include muscle tone of the trunk and extremities and joint mobility. Reassessing the neurologic criteria 18-24 hours after birth is best to allow for recovery from maternal medication (eg, magnesium sulfate, analgesics), which may decrease tone and responsiveness.

Hittner et al ⁹⁾ reported that regression of the vascularity of the lens capsule is an excellent tool to confirm a gestational age of 28-34 weeks.

How to calculate my baby’s corrected age?

When you’re judging whether your premature baby is developing normally, it is important to understand their ‘corrected age’.

The corrected age is your baby’s chronological age minus the number of weeks or months they were born early. For example, a 6-month-old baby who was born 2 months early would have a corrected age of 4 months. That means they may only be doing the things that other 4-month-olds do. Most pediatricians recommend correcting age when assessing growth and development until your child is 2 years old.

What is low birth weight?

Babies can be both premature and low birth weight.

Low birth weight is when babies weigh less than 2.5 kg (5 lbs. 8 oz.).

Low birth weight can happen because premature babies are born before they get the chance to put on weight in the last weeks or months of pregnancy. These babies have low birth weight but are the appropriate size for their gestational age.

What is extremely low birth weight?

An extremely low birth weight (ELBW) infant is defined as one with a birth weight of less than 1000 g (2 lb, 3 oz). Most extremely low birth weight infants are also the youngest of premature newborns, usually born at 27 weeks’ gestational age or younger. Infants born with a birth weight less than 1500 g are defined as very low birth weight (VLBW) infants.

Why are babies born prematurely?

The cause of premature birth is unknown in about half of all cases. However, some of the reasons babies are born prematurely include:

• multiple pregnancy (twins or more)
• the mother has a problem with her uterus or cervix, like uterine fibroids or a weakened cervix
• the mother gets an infection
• the mother has a medical condition that means the baby must be delivered early, such as pre-eclampsia
• the mother has a health condition like diabetes and high blood pressure
• a history of premature birth

There are also some other factors that are associated with a premature birth. These include poor or not enough nutrition, too much physical activity, smoking, alcohol and other drug use, too much stress, anxiety, depression, obesity, underweight and lack of prenatal care. Being under 17 years or over 35 years can also be a factor in premature birth.

The best way to make sure your pregnancy goes well is to follow your doctor’s advice about:

• eating well
• not smoking, not drinking alcohol and not taking other drugs
• doing the right amount of physical activity (some, but not too much)
• managing stress, depression and anxiety.

Even if you follow all the pregnancy advice, you might still have a premature baby. But if you look after yourself, you’ll have done the very best you can for your baby. If you think you might be at risk of premature birth, talk to your doctor or other health professional.

What will happen at the birth?

It is best for very premature babies to be born at a hospital that has a neonatal intensive care unit (NICU). If the hospital where the baby is born does not have an NICU, you and your baby may be transferred to another hospital.

When you are in labor, you may be given medicines to stop the contractions for a while. This allows you to be transferred to another hospital if necessary. You may also receive injections of corticosteroids 12 to 24 hours before the birth to help your baby’s lungs function more efficiently.

Premature babies can be born very quickly. They will usually be born through the vagina. However, in some cases the doctor may decide it is safest to deliver the baby via cesarean (C-section). Your doctor will discuss this decision with you.

A medical team from the neonatal (newborn) unit will be there for the birth. As soon as your baby is born, they will care for the baby in your room, possibly using a neonatal (baby) resuscitation bed. The team will keep your baby warm and help them to breathe with an oxygen mask or breathing tube, and possibly medicine. Some babies need help to keep their heart beating with cardio-pulmonary resuscitation (CPR) or an injection of adrenaline (epinephrine).

Once your baby is stable, they may be transferred to the NICU or special care nursery (SCN).

Respiratory management

• Recruitment and maintenance of optimal lung volume in infants with respiratory distress: This step can be accomplished with early use of continuous positive airway pressure (CPAP) given nasally, by nasal mask, or by using an endotracheal tube when mechanical ventilation and/or surfactant is administered
• Avoidance of hyperoxia or hypoxia with the aid of pulse oximetry: Always use blended oxygen with an oxygen saturation target range (SaO 2) of 90-95%. The lower limits of the pulse oximeter alarm should be set closer to the lower saturation limit, and the upper alarm limit should be no more than 95% ¹⁰⁾.
• Prevention or minimization of barotrauma or volutrauma should always be the goal when using a mechanical ventilator. Normal tidal volume is 4-7 mL/kg
• Early administration (age <2 hours) of surfactant is recommended when indicated. Routine use of prophylactic surfactant solely for prematurity is not advisable

Thermoregulation

It is very important to maintain normal temperature in any newborn, but this is particularly important for premature infants. Use radiant warmers with skin probes to regulate the desired temperature (in general, a normal body temperature of 36.5º-37.5ºC [97.7º-99.5ºF] ¹¹⁾. A heated and humidified isolette is ideal for extremely low birth weight (ELBW) infants. Food-grade plastic wrap/sheets can also be very helpful immediately after birth to control humidity and prevent heat loss in ELBW infants. The environmental temperature should be maintained to at least 25ºC (77º F) ¹²⁾.

Fluid and electrolyte management

Preterm infants require close monitoring of their fluid and electrolyte levels for several reasons (eg, immature skin increases transepidermal water loss; immature kidney function; the use of radiant warming, phototherapy, mechanical ventilation) ¹³⁾. The degree of prematurity dictates the initial fluid management. The following are general principles of fluid and electrolyte management when caring for premature infants:

• The initial fluid should be a solution of glucose and water
• Calcium may be added in the initial fluid
• Total parenteral nutrition should be started as early as possible, especially for ELBW infants

Close monitoring of glucose and electrolyte levels as well as acid-base balance is the key when managing ELBW infants. Strict monitoring of input and output is crucial. Thus, urine output, serum electrolyte levels, and daily weight are critical in handling fluids and electrolytes in premature infants.

What will my premature baby look like?

Premature babies look different from full-term babies. Their appearance depends on how early they were born.

When a baby is born at 34 to 37 weeks of gestation (late preterm), he’ll probably look like a small full-term baby.

As a baby’s gestational age decreases, her weight and size also decrease.

Extremely premature babies – for example, those born at 24 weeks of gestation – will be quite small and might fit snugly into your hand and look very fragile. They might look exhausted and have fragile, translucent skin. Their eyes might still be fused shut.

• Skin: it might not be fully developed, and may appear shiny, translucent, dry or flaky. The baby may not have any fat under the skin to keep them warm.
• Eyes: the eyelids of very premature babies may be fused shut at first. By 30 weeks they should be able to respond to different sights.
• Immature development: your baby might not be able to regulate its body temperature, breathing or heart rate. They may twitch, become stiff or limp or be unable to stay alert.
• Hair: your baby may have little hair on its head, but lots of soft body hair (called ‘lanugo’).
• Genitals: the baby’s genitals may be small and underdeveloped.

Without much body fat or muscle, premature babies tend not to move very much. Some of their first movements can be jerky. But as their muscles develop and their nerves start connecting to the brain, their movements become more smooth and controlled.

As these tiny babies grow, parents can watch the developmental changes in their baby’s appearance, movement and ability to interact with their world.

Premature baby diagnosis

Initial laboratory testing in cases of prematurity is performed to identify issues that, if corrected, improve the patient’s outcome.

Such tests include the following:

• Frequent blood glucose measurement: This is essential because premature infants are prone to hypoglycemia and hyperglycemia
• Complete blood count (CBC): Anemia or polycythemia may be revealed that is not clinically apparent
• White blood cell (WBC) count: A high or low WBC count and numerous immature neutrophil types may be found; an abnormal WBC count may suggest subtle infection
• Blood type and antibody testing (Coombs test): These studies are performed to detect blood-group incompatibilities between the mother and infant and to identify antibodies against fetal red blood cells (RBCs); such incompatibilities increase the risk for jaundice and kernicterus
• Serum electrolyte levels: Frequent determination of serum sodium, potassium, calcium, and glucose levels, in conjunction with monitoring of daily weight and urine output in extremely low birth weight (ELBW) infants, assist the clinician in managing fluid and electrolytes

Serum electrolytes analysis

At birth, most serum electrolyte levels reflect those of the mother. For example, if the mother received magnesium sulfate to inhibit labor, the baby’s respiratory effort may be compromised, and the serum magnesium value in the infant may be elevated.

The serum calcium may be low shortly after birth in small preterm babies.

Immature renal function, as well as limited bone and tissue reserves, result in the need for intravenous replacement of calcium, sodium, potassium, phosphate, and trace minerals in those infants who are taking nothing by mouth. Infants who can tolerate enteric nutrition receive adequate electrolytes and minerals from appropriate preterm formulas and fortified human milk.

Frequent laboratory determinations of serum sodium, potassium, calcium, and glucose levels in conjunction with monitoring of daily weight and urine output in extremely low birth weight (ELBW) infants assists the clinician in managing fluid and electrolytes.

Metabolic screening

Every state has a metabolic screening program. All programs include testing of newborn blood spots for a minimum of phenylketonuria, hypothyroidism, and galactosemia. The timing of obtaining the sample varies and a few samples may be required at different intervals. Referring to state guidelines can be very helpful.

In general, false-positive results are most common in preterm babies. Early detection and intervention minimizes the long-term neurologic risk.

Imaging studies

Imaging studies are specific to the organ system affected. Chest radiography is performed to assess the lung parenchyma and heart size in newborns with respiratory distress. Cranial ultrasonography is performed to detect occult intracranial hemorrhage in premature infants.

Lumbar puncture

Lumbar puncture is performed in premature infants with positive blood cultures and in those who have clinical signs of central nervous system infection. The decision to perform lumbar puncture in extremely low birth weight (ELBW) premature infants can sometimes be a difficult one because of their size and the surrounding clinical circumstances. However, when feasible, lumbar puncture should be performed; this will help in determining the duration of antibiotic therapy.

When will my premature baby be able to go home?

Premature babies often need time to “catch up” in both development and growth. In the hospital, this catch-up time may involve learning to eat and sleep, as well as steadily gaining weight. Depending on their condition, premature babies often stay in the hospital until they reach the pregnancy due date.

If a baby was transferred to another hospital for specialized NICU care, he or she may be transferred back to the “home” hospital once the condition is stable.

Your hospital will not send your baby home until they are confident both the baby and you are ready. Staff will make sure you understand how to care for your baby at home. They will also show you how to use any equipment you may need.

You will need appointments to see a neonatologist (newborn baby doctor) or pediatrician. Your local child and family health nurse will also see you regularly.

Consult your baby’s doctor for information about the specific criteria for discharge of premature babies at your hospital. General goals for discharge may include the following:

• Serious illnesses are resolved
• Stable temperature. The baby is able to stay warm in an open crib.
• Taking all feedings by breast or bottle
• No recent apnea or low heart rate
• Parents are able to provide care including medications and feedings

Before discharge, premature babies also need an eye examination and hearing test to check for problems related to prematurity. Parents need information about follow-up visits with the pediatrician for baby care and immunizations. Many hospitals have special follow-up healthcare programs for premature and low birthweight babies.

Even though they are otherwise ready for discharge, some babies continue to have special needs, such as extra oxygen or tube feedings. With instruction and the right equipment, these babies are often able to be cared for at home by parents. A hospital social worker can often help coordinate discharge plans when special care is needed.

Ask your baby’s doctor about a “trial run” overnight stay in a parenting room at the hospital before your baby is discharged. This can help you adjust to caring for your baby while healthcare providers are nearby for help and reassurance. Parents may also feel more confident taking their baby home when they have been given instructions in infant CPR (cardiopulmonary resuscitation) and infant safety.

Premature infants are at increased risk for sudden infant death syndrome (SIDS) and should be sleeping on their back before being sent home from the hospital. Please talk with your infant’s healthcare providers about these recommendations from the American Academy of Pediatrics to reduce the risk for SIDS and other sleep-related infant deaths in infants from birth to age 1:

• Make sure your baby is immunized. An infant who is fully immunized can reduce his or her risk for SIDS by 50 percent.
• Breastfeed your infant. The American Academy of Pediatrics recommends breastfeeding for at least six months.
• Place your infant on his or her back for sleep or naps. This can decrease the risk for SIDS, aspiration, and choking. Never place your baby on his or her side or stomach for sleep or naps. If your baby is awake, allow your child time on his or her tummy as long as you are supervising, to decrease the chances that your child will develop a flat head and strengthen the baby’s stomach muscles.
• Always talk with your baby’s doctor before raising the head of their crib if he or she has been diagnosed with gastroesophageal reflux.
• Offer your baby a pacifier for sleeping or naps, if he or she isn’t breastfed. If breastfeeding, the AAP recommends delaying the introduction of introducing a pacifier until breastfeeding has been firmly established. If your baby has already been taking a pacifier before he or she was mature enough to feed directly from the breast, don’t panic. Ask for help from a lactation consultant for the transition to feeding from the breast if the baby is strong enough to do so.
• Use a firm mattress (covered by a tightly fitted sheet) to prevent gaps between the mattress and the sides of a crib, a play yard, or a bassinet. This can decrease the risk for entrapment, suffocation, and SIDS.
• Share your room instead of your bed with your baby. Putting your baby in bed with you raises the risk for strangulation, suffocation, entrapment, and SIDS. Bed sharing is not recommended for twins or other higher multiples.
• Avoid using infant seats, car seats, strollers, infant carriers, and infant swings for routine sleep and daily naps. These may lead to obstruction of an infant’s airway or suffocation.
• Avoid using illicit drugs and alcohol, and don’t smoke during pregnancy or after birth.
• Avoid overbundling, overdressing, or covering an infant’s face or head. This will prevent him or her from getting overheated, reducing the risks for SIDS.
• Avoid using loose bedding or soft objects?bumper pads, pillows, comforters, blankets?in an infant’s crib or bassinet to help prevent suffocation, strangulation, entrapment, or SIDS.
• Avoid using cardiorespiratory monitors and commercial devices?wedges, positioners, and special mattresses?to help decrease the risk for SIDS and sleep-related infant deaths.
• Always place cribs, bassinets, and play yards in hazard-free areas?those with no dangling cords or wires?to reduce the risk for strangulation.

It is normal to feel a little worried when you are looking after your baby yourself after so long in hospital. Take it slowly in a calm and quiet environment until you both get used to being at home.

Taking care of your premature baby

Your premature baby’s bones

A premature baby’s bones aren’t always fully developed. In the last months of pregnancy, lots of minerals – including calcium and phosphorus – are transferred from mother to baby. In a full-term baby, this helps bones grow and get strong. But premature babies don’t get these important minerals in the womb.

Premature babies also often lose more minerals through their urine than full-term babies.

And full-term babies spend their last few months in the womb stretching and flexing their muscles, which also helps their bones to develop. Premature babies miss out on this too.

It can take quite a while for your premature baby’s bones to grow and get strong.

Helping your premature baby’s bones to grow

Staff in the neonatal intensive care unit (NICU) might recommend a powder containing supplementary calcium and phosphorus that can be added to expressed breastmilk for premature babies. This helps their bones grow and strengthen. Sometimes a specially formulated and fortified formula milk can be used.

Gentle exercises specially designed for premature babies – for example, bending and straightening their arms and legs – can help your baby gain weight and build stronger bones and larger muscles. These exercises can also make it less likely that your baby’s motor development will be delayed.

These exercises need to fit into your premature baby’s overall medical plan, so speak to your doctor before you try them. Your baby’s doctor will know when your baby is ready to start exercises. A hospital physiotherapist will probably do these special exercises with your baby to start with, while you learn how to do them.

When you take your premature baby home, you can play games that encourage her to move her arms and legs. For example, let your baby kick while lying on the floor, or play ‘Row, row, row your boat’ while gently moving your baby’s arms.

Your premature baby’s skin

When a premature baby is born, his skin might not be fully developed. It develops quickly, though.

Skin has two very important functions. It lets your baby sense the world through touch and temperature. It also protects all the vulnerable tissues and organs inside your baby’s body.

Sensation

Touch is the first of the senses to mature. Your premature baby learns about the world mainly through touch, and touch is a key way for you to bond with your premature baby.

It can be soothing for your premature baby if you warm your hands and place them gently on her back or head. Just keep them still. Too much pressure or the wrong kind of touch can be stressful for your baby. Your baby’s nurse will show you how to touch your baby to soothe and comfort her.

Protection

In a full-term baby, the skin acts as a barrier against bacteria and viruses that can infect the body. The fat under the skin also insulates the baby by keeping in heat and fluid. It prevents dehydration too.

Sometimes, the skin of very small premature babies – those born at around 26 weeks – hasn’t fully developed. It might look smooth and shiny or translucent, and it’s very fragile. It doesn’t yet act as an efficient barrier. So if anything gets on the baby’s skin, the hair follicles and glands might let it through – for example, any lotions or creams put onto the skin.

Later – at 30-32 weeks – your baby’s skin might look wrinkly and loose, because the skin surface has increased, but your baby doesn’t have much fat underneath the skin.

Because premature babies sometimes have very little fat, they can’t keep a steady body temperature. Your baby’s incubator will be warmed and might be humidified until his skin strengthens 2-3 weeks after birth.

It’s also normal for premature babies’ skin to get dry and flaky.

Taking care of your premature baby’s skin

Each NICU will have its own procedures for looking after premature babies’ fragile skin. For example, your NICU might use oil or cream for premature babies with very dry skin, and staff will take care handling premature babies with very fragile skin.

You can also help to care for your premature baby’s skin by:

• using soft cotton baby clothes rather than synthetics that don’t breathe or wool that can be scratchy
• not putting anything onto your baby’s skin without first checking with the nurse or doctor
• learning how best to touch your baby – your baby’s nurse or doctor will be able to help you.

Premature baby’s development

Some common issues for premature babies include:

• breathing problems
• heart problems
• problems in their digestive tract
• jaundice
• anemia
• infections

Most premature babies will develop normally, but they are at higher risk of developmental problems so will need regular health and development checks at the hospital or with a pediatrician. If you are worried about your child’s development, talk to your doctor.

Problems that may occur later in children who were born prematurely include:

• language delays
• growth and movement problems
• problems with teeth
• problems with vision or hearing
• thinking and learning difficulties
• social and emotional problems

Do premature babies need special medical care?

Talk to your baby’s health care providers about any health conditions your baby has. He may be healthy enough to go home soon after birth, or he may need to stay in the NICU for special care. Your baby can probably go home from the hospital when he:

• Weighs at least 4 pounds
• Can keep warm on his own, without the help of an incubator. An incubator is a clear plastic bed that helps keep your baby warm.
• Can breastfeed or bottle-feed
• Gains weight steadily
• Can breathe on his own

Your baby may need special medical equipment, medicine or other treatment after he leaves the hospital. Your baby’s provider and the staff at the hospital can help you with these things and teach you how to take care of your baby at home. They may recommend that you bring your baby to a neonatologist for checkups after your baby leaves the hospital. A neonatologist is a doctor who specializes in caring for premature babies and children. Talk to your baby’s provider if you have any questions about your baby’s health or long-term effects of premature birth. Hospital staff also can help you find parent support groups and other resources in your area that may be able to help you care for your baby.

What kinds of health problems can premature babies have?

Health problems that may affect premature babies include:

• Anemia. This is when a baby doesn’t have enough healthy red blood cells to carry oxygen to the rest of the body. Anemia can cause low levels of oxygen and glucose (sugar) in a baby’s blood and make it hard for a baby’s organs to work properly. Premature babies in the NICU may have anemia because they get regular blood tests to check their health. They often can’t make new blood cells quickly enough to replace the blood cells they lose during blood tests. This can lead to anemia.
• Breathing problems. These include:
  • Apnea of prematurity also called AOP. This is a pause in breathing for 15 to 20 seconds or more. It may happen together with a slow heart rate called bradycardia.
  • Bronchopulmonary dysplasia also called BPD. This is a lung disease that can develop in premature babies as well as babies who have treatment with a breathing machine. Babies with bronchopulmonary dysplasia have a higher risk of lung infections than other babies and bronchopulmonary dysplasia sometimes leads to lung damage.
  • Respiratory distress syndrome also called RDS. If a baby has respiratory distress syndrome, her lungs can’t make enough of a substance called surfactant. Surfactant is a slippery substance that keeps small air sacs in a baby’s lungs from collapsing.
• Infections or neonatal sepsis. Premature babies can get infections more easily than other babies because their immune systems aren’t fully developed. The immune system protects your body from infection. Infection in premature babies can lead to sepsis, when the body has an extreme response to infection. Sepsis can be life-threatening.
• Intraventricular hemorrhage also called IVH. This is bleeding in the fluid-filled spaces also called ventricles in the brain. The more premature a baby is, the more likely he is to have intraventricular hemorrhage.
• Newborn jaundice. This is when your baby’s skin and the white parts of his eye look yellow. It’s caused by the build-up of a substance called bilirubin in your baby’s blood. Jaundice happens when a baby’s liver isn’t fully developed or isn’t working well.
• Necrotizing enterocolitis also called NEC. This is a common, but very serious problem that can affect a newborn baby’s intestines. Intestines are long tubes that are part of your digestive system. Your baby’s digestive system helps his body break down food, take in nutrients and remove waste. Necrotizing enterocolitis happens when the tissue of the intestine is injured (damaged) or begins to die.
• Patent ductus arteriosus also called PDA. This is a heart condition that happens when a blood vessel called the ductus arteriosus doesn’t close properly. The ductus arteriosus helps blood go around a baby’s lungs before birth. Once a baby’s born and her lungs fill with air, the ductus arteriosus isn’t needed anymore and usually closes on its own a few days after birth. If it doesn’t close properly, too much blood may flow into the lungs. This can cause heart and breathing problems.
• Retinopathy of prematurity also called ROP. This is an eye disease that happens when a baby’s retina’s don’t fully develop in the weeks after birth. The retina is the nerve tissue that lines the back of the eye. Retinopathy of prematurity usually affects both eyes. Most babies with retinopathy of prematurity have a mild case and don’t need treatment. But babies with severe retinopathy of prematurity can have vision problems or blindness.

Prematurity prognosis

Mortality and morbidity are inversely proportional to gestational age and birth weight. Infants with extremely low birth weight (ELBW) who are born at tertiary care centers have outcomes more favorable than those who are born at level 1 or 2 centers and then transferred.

Roberts et al ¹⁴⁾ found that children born at 22-27 weeks’ gestation have high rates of adverse neuro-developmental outcome at age 8 years. Assessment of a regional cohort of 144 survivors of preterm birth showed that, relative to matched term controls, the preterm cohort had substantially higher rates of blindness, deafness, cerebral palsy, and intellectual impairment and disabilities caused by these impairments. Comparison of preterm children born in 1997 with those born in 1991-1992 showed that the rates of moderate or severe disability were similar in the two cohorts (19%), but the rate of mild impairment was greater in 1997 (40% vs 24%); disability rates in control groups showed virtually no change over time ¹⁵⁾.

Infants born at born at 23-25 weeks of gestation who receive antenatal exposure to corticosteroids appear to have a lower rate of mortality and complications compared with those who do not have such exposure ¹⁶⁾. Infants born at at 34-36 weeks’ gestation with antenatal exposure to corticosteroids between 24 and 34 weeks of gestation also appear to have a lower incidence of respiratory disorders ¹⁷⁾.

Morbidity and mortality

Preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths, as well as 25-50% of cases of long-term neurologic impairment in children ¹⁸⁾.

The mortality rate is high in developing countries, especially those of Sub-Saharan Africa. The perinatal mortality rate is 70 deaths per 1000 births; the neonatal mortality rate is 45 deaths per 1000 live births. Preterm birth is the strongest independent predictor of mortality in the United States. Preterm delivery accounts for 75-80% of all neonatal morbidity and mortality.

Since the early 1960s, survival rates of premature infants substantially increased because of technologic advances. From 1989-1990, infants with birth weights less than 751 g had a survival rate of 39% (range among centers, 23-48%). In 1992, the US Food and Drug Administration (FDA) approved exogenous surfactant therapy for respiratory distress syndrome (RDS), leading to a considerable improvement in survival rates. Since the FDA approved the use of surfactant and since the subsequent introduction of numerous natural surfactants, the mortality rate attributed to surfactant deficiency has been markedly reduced.

Data from the Vermont Oxford Network in 1994-1996 indicated that the survival rate of infants born weighing less than 1000 g was 74.9% ¹⁹⁾. Survival of infants born weighing less than 1000 g and requiring cardiopulmonary resuscitation in the delivery room was substantially decreased (53.8%). The changes in obstetric and neonatal care in the first half of the decade of 1990s decreased mortality and morbidity for ELBW infants. No additional improvements in mortality and morbidity were observed at the end of the decade.

Obstetric and pediatric personnel must be familiar with their own institutional data in addition to national benchmarks related to gestational age and mortality rates. These data are essential for proper prenatal counseling of parents and/or caregivers regarding survival and resuscitation plans.

The three primary causes of mortality in infants born with a weight of less than 1000 g are respiratory failure, infection, and congenital malformation. Infection of the amniotic fluid leading to pneumonia is the major cause of mortality ²⁰⁾. In infants who weigh less than 500 g at birth, immaturity is listed as the only cause of mortality.

Women who have an intrauterine infection do not respond to tocolytics. Preterm premature rupture of membranes (PPROM) is associated with 30-40% of premature deliveries. Mortality of the premature infant increases with coexisting PPROM but depends on gestational age and the expertise of the maternal-fetal monitoring team. Postnatal findings of periventricular leukomalacia (PVL) on cranial ultrasonography are highly correlated with chorioamnionitis.

In premature infants with a congenital heart disease (CHD), excluding isolated patent ductus arteriosus, the actuarial survival rate is 51% at 10 years, whereas infants with both congenital heart disease and prematurity have substantially worsened outcomes than infants who only have one of these conditions ²¹⁾. The survival rate improved as the study period (1976-1999) progressed. Congenital anomalies are an independent risk factor for mortality and morbidity in preterm birth.

In a longitudinal study of 1279 extremely premature children, (gestational age ≤28 week; birth weight ²²⁾. Among affected children, hearing loss was delayed in onset in 10% and progressive in 28%. Prolonged supplemental oxygen use was the most important marker for predicting hearing loss.

In a retrospective analysis of data from 20,231 live births recorded between 1995 and 2003, Werner et al found that very premature infants who are delivered vaginally have fewer breathing problems than do those delivered by cesarean section ²³⁾. All of the study’s infants were born after 24-34 weeks’ gestation, with 69.3% of them delivered vaginally. In comparison with the vaginally delivered infants, those delivered by cesarean section were more likely to be born in respiratory distress (39.2% compared with 25.6% for vaginal delivery). Infants in the study who underwent cesarean delivery were also more likely than vaginally delivered infants to have a 5-minute Apgar score of less than 7 (10.7% vs 5.8%, respectively) ²⁴⁾.