Intrauterine growth restriction

Intrauterine growth restriction (IUGR) also called fetal growth restriction (FGR), is a medical term that describes a baby who is not growing at the normal rate inside the uterus during the pregnancy. In other words, at any point in the pregnancy, the baby is not as big as would be expected for how far along the mother is in her pregnancy, this timing is referred to as an unborn baby’s “gestational age”. These babies usually have a low weight at birth.

Babies who have IUGR or fetal growth restriction often have a low weight at birth. If the weight is below the 10th percentile for a baby’s gestational age (meaning that 90% of babies that age weigh more) the baby is also referred to as “small for gestational age” or SGA.

It’s important to note that not all babies who are small for gestational age had intrauterine growth restriction while in the womb. For example, some are healthy babies who are just born smaller than average because their parents are small in stature.

The two types of intrauterine growth restriction are:

1. Symmetrical IUGR, in which a baby’s body is proportionally small (meaning all parts of the baby’s body are similarly small in size).
2. Asymmetrical IUGR, which is when the baby has a normal-size head and brain but the rest of the body is small.

During your pregnancy, your doctor will do tests to find out if your baby is growing normally. The main test for checking a baby’s growth in the uterus is an ultrasound. The ultrasound exam lets your doctor see your baby in your uterus with an instrument that is moved across your abdomen.

While you are having an ultrasound exam, your doctor will measure the size of your baby’s head, abdomen, and legs. These measurements will tell you and your doctor if your baby is growing normally. Your doctor will also find out the amount of amniotic fluid in your uterus. In some babies who have IUGR, the amount of amniotic fluid is low. If your baby is small, you may need more frequent ultrasound exams to check your baby’s health.

Another test is fetal monitoring. It’s a way to check your baby’s health inside your uterus. Monitoring devices are strapped over your uterus as you lie down for about 30 minutes. You will hear your baby’s heartbeat as it is recorded. Your doctor can look at the recording and see if your baby’s heartbeat is normal.

More tests may be needed to screen for infection or genetic problems if IUGR is suspected.

You might also have an amniocentesis. During this test, a needle is put through your skin into your uterus. A few teaspoons of amniotic fluid are withdrawn in the needle. The fluid is tested to see if it shows the cause of the IUGR. The amniotic fluid can detect infection and some chromosomal abnormalities that can cause genetic problems.

When a woman learns that her baby has or might have IUGR, the best way to help your baby is to keep all of your prenatal visits with your doctor. You should also monitor how often your baby moves and kicks. A baby who moves around often is usually healthy. A baby who doesn’t move very often or who stops moving may be sick. If you notice your baby isn’t moving as much, see your doctor.

Another way you can help your baby is to take good care of your body. Eat plenty of healthy foods and take in the recommended amount of calories for a pregnant woman. Rest will help you feel better and it may even help your baby grow. Try to get 8 hours of sleep (or more) each night. An hour or 2 of rest in the afternoon is also good for you. Finally, if you smoke, drink alcohol, or use drugs, stop now. These things can hurt your baby. This may be all that is needed to improve your baby’s health, as well as your own.

Management depends on how serious the intrauterine growth restriction is. This is based on the ultrasound (estimated fetal weight) and Doppler ultrasound (blood flow to the baby), as well is risk factors and the number of weeks gestation.

Treatment may include:

• Frequent monitoring. This means you will have prenatal visits more often, and ultrasound and Doppler ultrasound exams. You may have other tests.
• Tracking fetal movements. Your healthcare provider may also ask you to keep track of fetal movements. If so, he or she will give you instructions.
• Corticosteroid medicine
• Hospital stay
• Early delivery or emergency cesarean

If my baby has intrauterine growth restriction, will I have to give birth early?

Maybe not. The time of delivery depends on how well your baby is doing. Sometimes, babies with intrauterine growth restriction keep on growing in the uterus. If your baby keeps gaining some weight, an early delivery may not be needed. But if your baby is not growing at all or has other problems, your doctor may decide that an early delivery could help. In this case, your doctor may want to induce labor. Your baby’s heart rate and movements will be closely watched to help you and your doctor make this decision.

Will I need to have a cesarean section?

If there are no signs of problems with your baby during labor, a vaginal delivery is okay. Some babies with intrauterine growth restriction are weak. The stress of labor and delivery may be too much for a weak baby. If your baby has problems during labor, a cesarean section or a C-section may be safer.

Will my baby need to stay in the hospital longer than usual?

Probably, especially if your baby was born early. Babies who are small at birth need to stay in the hospital until they can breathe and feed normally. After your baby is born, the doctor will check your baby’s weight to make sure the baby is growing. Generally, babies stay in the hospital until they weigh about 5 pounds and can breathe and feed normally.

Do all small babies have intrauterine growth restriction?

No. About one-third of the babies who are small at birth have IUGR. The rest of them don’t have IUGR—they’re just smaller than normal. Just like there are different sizes of infants, children, and adults, there are also different sizes of babies in the uterus. Small babies tend to run in families. The parents or other children in the family may have been small when they were born, too.

If I have another baby, will that baby also have intrauterine growth restriction?

Generally, no. Intrauterine growth restriction usually doesn’t occur in another pregnancy. But in some women, it does happen again. Women who have another pregnancy affected by IUGR usually have an illness, such as hypertension, that causes IUGR. Good control of illnesses before and during pregnancy lowers the risk of having another baby with intrauterine growth restriction.

Intrauterine growth restriction causes

Intrauterine growth restriction or IUGR has various causes. The most common cause is a problem in the placenta (the tissue that carries oxygen, food, and blood to the baby), which prevents a baby from getting enough oxygen and nutrients. This lack of nourishment slows the baby’s growth. It can happen for a number of reasons. A common cause is placental insufficiency, in which the tissue that delivers oxygen and nutrients to the baby is not attached properly or isn’t working correctly.

Birth defects and genetic disorders can also cause intrauterine growth restriction.

If the mother is small, it may be normal for her baby to be small, but this is not due to intrauterine growth restriction.

Most of the causes of IUGR are beyond your control. Usually, nothing the mother did causes IUGR in her baby. But if you smoke cigarettes, drink alcohol, or abuse drugs, you can cause intrauterine growth restriction in your baby.

Depending on the cause of intrauterine growth restriction, the developing baby may be small all over. Or, the baby’s head may be normal size while the rest of the body is small.

An unborn baby may not get enough oxygen and nutrition from the placenta during pregnancy because of:

• High altitudes
• Multiple pregnancy, such as twins or triplets
• Placenta problems
• Preeclampsia or eclampsia

A baby may develop IUGR if the mother:

• Has an infection.
• Has high blood pressure.
• Has kidney disease.
• Has heart disease.
• Has too few red blood cells (anemia) e.g., sickle cell anemia.
• Has blood clotting disorders.
• Has diabetes.
• Has poor nutrition.
• Has very low weight.
• Has a large amount of excess weight (obese).
• Is smoking.
• Is drinking alcohol.
• Is abusing drugs.
• Has other chronic disease e.g., autoimmune conditions such as lupus.

Sometimes a prescribed medicine that the mother is taking causes IUGR.

Problems at birth (congenital abnormalities) or chromosome problems are often associated with below-normal weight.

Factors in the baby that can cause intrauterine growth restriction include:

• Being one of a twin or triplets
• Infections
• Birth defects, such as heart defects
• Problem with genes or chromosomes

Infections during pregnancy can also affect the weight of the developing baby. These include:

• Cytomegalovirus
• Rubella
• Syphilis
• Toxoplasmosis

Risk factors for intrauterine growth restriction

Intrauterine growth restriction is more likely to occur in women who are carrying more than one baby or who had a previous baby who was small for gestational age or had intrauterine growth restriction. Certain medical conditions, such as some types of heart, lung, blood, or autoimmune disease, and anemia also can increase a woman’s risk of developing intrauterine growth restriction. So can eating poorly or being underweight before or during pregnancy.

Intrauterine growth restriction prevention

Intrauterine growth restriction can happen in any pregnancy. But some factors, like cigarette smoking or alcohol or medicine use, increase the risk for intrauterine growth restriction. Regular and early prenatal care and a healthy diet and steady weight gain help to prevent intrauterine growth restriction and other problems.

Following these guidelines will help prevent intrauterine growth restriction:

• Do not drink alcohol, smoke, or use recreational drugs.
• Eat healthy foods.
• Get regular prenatal care.
• If you have a chronic medical condition or you take prescribed medicines regularly, see your doctor before you get pregnant. This can help reduce risks to your pregnancy and the baby.

Intrauterine growth restriction symptoms

A pregnant woman doesn’t have symptoms of intrauterine growth restriction. A pregnant woman may feel that her baby is not as big as it should be. The measurement from the mother’s pubic bone to the top of the uterus will be smaller than expected for the baby’s gestational age. This measurement is called the uterine fundal height.

One of the main reasons for regular prenatal exams is to make sure your baby is growing well. During pregnancy, the size of your baby is estimated in different ways, including:

• Fundal height. To check fundal height, your healthcare provider measures from the top of your pubic bone to the top of your uterus (fundus). Fundal height, measured in centimeters (cm), is about the same as the number of weeks of pregnancy after the 20th week. For example, at 24 weeks gestation, your fundal height should be close to 24 cm. If the fundal height is less than expected, it may mean intrauterine growth restriction.

IUGR may be suspected if the size of the pregnant woman’s uterus is small. Intrauterine growth restriction is most often confirmed by ultrasound.

During an ultrasound, a technician coats the woman’s belly with a gel and then moves a probe (wand-like instrument) over it. High-frequency sound waves “echo” off the body and create pictures of the baby on a computer screen. These pictures can be used to estimate the baby’s size and weight.

Although these estimates might not be exact, they help health care providers track the baby’s growth and see if there’s a problem. Ultrasounds also can help identify other issues, such as problems with the placenta or low amniotic fluid levels.

But a baby with intrauterine growth restriction may have certain signs after birth, such as:

• Low birth weight
• Low blood sugar levels
• Lower body temperature
• High level of red blood cells
• Trouble fighting infections.

Intrauterine growth restriction complications

Intrauterine growth restriction increases the risk of pregnancy and newborn complications, depending on the cause. Babies whose growth is restricted often become more stressed during labor and need C-section delivery.

Your baby may need to be delivered early and stay in the hospital. Your baby may have trouble breathing, infections, and other problems. Stillbirths and death may occur. As your child grows, he or she will be at higher risk for heart and blood vessel problems.

Intrauterine growth restriction diagnosis

Since not all babies who are small have intrauterine growth restriction, an accurate diagnosis is important. This starts with correctly determining the baby’s gestational age by accurately dating the pregnancy.

At first, gestational age is estimated using the first day of a woman’s last menstrual period. Later in the pregnancy (usually between weeks 8 and 13), it is confirmed through an ultrasound. Once a baby’s gestational age is known, doctors use it to watch the baby’s growth and compare it with the expected growth rate. If the baby is growing more slowly than expected (sometimes referred to as “small for dates”), doctors will continue to watch the baby’s growth and may do more tests to see whether the baby has intrauterine growth restriction.

Watching growth is done in several ways. A measurement called the uterine fundal height helps estimate a baby’s size by measuring a mother’s belly from the top of the pubic bone to the top of the uterus.

Another way is to use ultrasounds. In fact, intrauterine growth restriction is usually diagnosed through an ultrasound examination.

If your healthcare provider thinks you have intrauterine growth restriction, you will have ultrasound tests. These include:

• Fetal ultrasound. Estimating fetal weight with ultrasound is the best way to find intrauterine growth restriction. Ultrasound uses sound waves to create images of the baby in the womb. Sound waves will not harm you or the baby. Your healthcare provider or a technician will use the images to measure the baby. A diagnosis of intrauterine growth restriction is based on the difference between actual and expected measurements at a certain gestational age.
• Doppler ultrasound. You may also have this special type of ultrasound to diagnose intrauterine growth restriction. Doppler ultrasound checks the blood flow to the placenta and through the umbilical cord to the baby. Decreased blood flow may mean your baby has intrauterine growth restriction.

You may have repeat ultrasound exams, Doppler studies, and other tests.

Your doctors also might do other tests if they believe a baby has intrauterine growth restriction, such as:

• Fetal monitoring to track the baby’s heart rate and movements
• Screenings for infections
• Amniocentesis to help find the cause of intrauterine growth restriction (and sometimes to help determine lung maturity and whether the baby is likely to be able to breathe on his or her own)

Intrauterine growth restriction treatment

When intrauterine growth restriction is diagnosed, treatment is decided based on your baby’s condition and the woman’s month of pregnancy.

Intrauterine growth restriction increases the risk that the baby will die inside the womb before birth. If your doctor thinks you might have intrauterine growth restriction, you will be monitored closely. This will include regular pregnancy ultrasounds to measure the baby’s growth, movements, blood flow, and fluid around the baby – to keep track of growth and watch for other potential problems.

Nonstress testing will also be done. This involves listening to the baby’s heart rate for a period of 20 to 30 minutes.

Treatment also might include managing any maternal illness and ensuring that the mother eats a healthy and nutritious diet and gains the appropriate amount of weight. Some women are placed on bed rest to try to improve blood flow to the baby.

Depending on the results of these tests, your baby may need to be delivered early.

In some cases, health care providers will recommend inducing labor and delivery early if monitoring shows that a baby has stopped growing or has other problems. Although early delivery might be necessary, the goal is to keep the baby safe in the womb for as long as possible.

A cesarean section (C-section) might be done if the stress of a vaginal delivery is considered too risky for the baby.

Intrauterine growth restriction prognosis

After delivery, the newborn’s growth and development depends on the severity and cause of intrauterine growth restriction. Unfortunately, babies with intrauterine growth restriction are more likely to have health problems both before and after birth. Discuss your baby’s outlook with your doctor.

In general, babies who are born prematurely or are very small at birth are more likely to have problems that result in longer hospital stays. They also might need special care after birth, such as help breathing or medicine to prevent infections.

Other problems that can be related to intrauterine growth restriction include:

• increased likelihood of C-section delivery
• problems with breathing and feeding
• trouble maintaining body temperature
• abnormal blood cell counts
• low blood sugar level (hypoglycemia)
• decreased ability to fight infection
• neurological problems
• increased likelihood of stillbirth (dying in the womb before birth)

Babies who have intrauterine growth restriction are more likely to have certain health problems both during pregnancy and after birth. Problems include:

• A difficult time handling the stress of vaginal delivery.
• Increased risk of being stillborn.
• Low blood sugar level at birth.
• Lower resistance to infection.
• Trouble maintaining body temperature.
• An abnormally high red blood cell count.

The long-term effects of intrauterine growth restriction may depend on the condition that caused the problem in the first place.

Will my baby grow up to be normal in height?

Your baby will probably catch up in size and have a normal height by about 2 years of age.