Fetal Growth Restriction

Last Updated June 2022 | This article was created by familydoctor.org editorial staff and reviewed by Robert "Chuck" Rich, Jr., MD, FAAFP

What is fetal growth restriction (FGR)?

Fetal growth restriction (FGR), previously called intrauterine growth restriction, is a term that describes an unborn baby who isn’t growing at the normal rate inside the uterus. These babies usually have a low weight at birth.

Symptoms of FGR

Some babies are born smaller than normal. However, only about one-third of those babies were affected by growth restriction in pregnancy.

Small babies tend to run in families. The parents or other children in the family may have been small when they were born, too.

Babies who have FGR are more likely to have certain health problems (both during pregnancy and after birth), including:

  • 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

What causes FGR?

The most common cause of FGR is a problem before birth in the placenta (the tissue that carries oxygen, food, and blood to the baby). Birth defects and genetic disorders can also cause FGR.

A baby also may develop FGR if the mother:

  • Has an infection
  • Has high blood pressure
  • Has kidney disease
  • Has heart disease
  • Has sickle cell anemia
  • Has diabetes prior to pregnancy
  • Smokes
  • Drinks alcohol
  • Abuses drugs

Sometimes a prescribed medicine the mother is taking causes FGR. Babies with genetic conditions such as Down syndrome are also more likely to have FGR.

How is FGR diagnosed?

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 the outside of your abdomen.

While you’re having an ultrasound, your doctor will measure the size of your baby’s head, abdomen, and legs. These measurements will tell him or her if your baby is growing normally. Your doctor will also be able to see the amount of amniotic fluid in your uterus. In some babies who have FGR, 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 to check inside your uterus is fetal monitoring. Monitoring devices are strapped over your uterus as you lie down for about 30 minutes. The devices record your baby’s heartbeat. Your doctor can look at the recording and see if your baby’s heartbeat is normal.

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 A few teaspoons of amniotic fluid are withdrawn into the needle.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

Can FGR be prevented or avoided?

If you smoke cigarettes, drink alcohol, or use drugs, stop now. These things can cause FGR.

Having FGR in one pregnancy doesn’t mean it will happen the next time. If you do have another pregnancy affected by FGR, you may have an illness, such as hypertension. Good control of illnesses before and during pregnancy lowers the risk of FGR.

FGR treatment

The best way to help your baby is to keep all 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, call your doctor right away.

Another way to help your baby is to take good care of your body. Eat healthy foods and make sure you eat the recommended number of calories for a pregnant woman. 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. Rest will not only help you feel better, it may even help your baby grow.

Living with FGR

If your baby has FGR, you may give birth early. The time of delivery depends on how well your baby is doing. Sometimes, babies with FGR appear to be small but healthy. If testing suggests that the pregnancy is not developing well, 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.

If there are no signs of problems with your baby during labor, a vaginal delivery is okay. If your baby has problems during labor, a cesarean section (also called a C-section) may be safer.

A baby born with FGR usually needs to stay in the hospital longer after birth. This is especially true for babies born early. They need to breathe and feed normally before they can go home.

Babies born with FGR often catch up in size and have a normal height and weight by about 2 years of age. In the meantime, they should be fed normally without attempting to catch up quicker.

Questions to ask your doctor

  • Does my baby have fetal growth restriction (FGR)?
  • What is the likely cause of FGR?
  • How often do I need an ultrasound?
  • Is there anything I can do to decrease my baby’s risk?
  • What lifestyle changes can I make at home to make sure my baby is healthy?
  • After my baby is born, what health problems is he/she at risk for?
  • How long might my baby stay in the hospital after birth?