FGR can be caused by certain problems with the mother’s health, problems with the fetus, or problems with the placenta. The following health conditions in the mother increase the risk of FGR:

• Preexisting diabetes, heart disease, kidney disease, or lupus

• High blood pressure that occurs during pregnancy

• Smoking, using illegal drugs, or drinking alcohol

• Infections

• Taking medications or being exposed to certain harmful chemicals

Fetal health conditions that can cause FGR include the following:

• A genetic condition, such as an abnormal number of chromosomes (a condition known as aneuploidy)

• A problem that affects a body structure, like the heart or the digestive tract

• Fetal infection

A problem with the placenta is the most common cause of FGR. If the placenta is not working well, the fetus may not get enough nutrients to grow normally.

Being pregnant with more than one baby is also a common cause of FGR. The odds of twins being born too small are as high as 1 in 5. For triplets, the odds are 3 in 5.

Babies with severe FGR have an increased risk of breathing problems, low blood sugar, and problems staying warm. They may need special care in the neonatal intensive care unit. In very serious cases, there is an increased risk of stillbirth or the baby dying after birth.

Your healthcare provider will check how your fetus is growing during your regular prenatal care visits. Two ways are used to estimate fetal growth:

• Fundal height: In the second half of pregnancy, your healthcare professional will measure your abdomen from the pubic bone to the top of the uterus (the fundus). This measurement is called the fundal height. Your fundal height in centimeters should be about the same as the number of weeks of pregnancy. For example, at 24 weeks of pregnancy, your fundal height should be around 24 centimeters. Fundal height measurement may not work as well in people who are obese or who are pregnant with more than 1 baby.

• Ultrasound exam: Certain parts of the fetus are measured during an ultrasound exam, such as how big around the head and abdomen are and the length of the thigh bone. These measurements are used along with gestational age to estimate the fetal weight.

FGR is not caused by working too much, anxiety, or a vegetarian diet. Eating a balanced diet, exercising, and avoiding smoking and illegal drugs can help the fetus grow well. If you do have an underlying health condition (such as diabetes or high blood pressure), following your treatment plan to keep it under control can also help.  In most cases, FGR isn’t related to anything you’ve done or haven’t done.

It’s actually hard to diagnose FGR just by looking at someone. But if you’re concerned about your size, tell your healthcare provider.

There is no treatment for FGR, but it can be managed to reduce the chance of complications. Sometimes, this means delivering the fetus earlier than the due date by labor induction or possibly by cesarean delivery. Early delivery is recommended when continuing the pregnancy might increase the risk of further complications.

When FGR is first diagnosed, you may have tests to find the cause of the growth problem, particularly if it is early in pregnancy. In the third trimester, fetal testing may also be used to check the fetus’s well-being and decide the best time to deliver. The following tests may be offered to manage and monitor FGR depending on the time in your pregnancy when FGR is diagnosed:

• Detailed ultrasound exam: This ultrasound exam looks at the fetus’s body in detail to see if there are any physical abnormalities. The amount of amniotic fluid is also measured.

• Genetic testing with amniocentesis: This test is offered if there is a concern that a chromosomal disorder may be present.

• Electronic fetal heart rate monitoring: This test involves putting monitors on your abdomen to assess the fetal heart rate and contractions over time. Changes in the fetal heart rate can tell your care providers if the placenta is working as expected. It may be performed weekly or more often if necessary.

• Biophysical profile and Doppler ultrasound: In a biophysical profile, ultrasound is used to help measure the baby’s movements, breathing, muscle tone, and amount of amniotic fluid. A Doppler ultrasound shows blood flow through an artery in the umbilical cord, which helps assess how the placenta is working.

No. Bed rest should not be used to treat FGR. It has not been shown to improve outcomes. In fact, bed rest can cause harm by increasing the risk of bone loss, muscle loss, and blood clots.

The goal of monitoring is to help you and your healthcare professional decide the best time to deliver the baby. If test results show that the fetus is not doing well, early delivery may be recommended. If delivery is before term, there can be another set of problems related to prematurity.

Deciding the right time for delivery involves balancing the risks of being born too early versus the risks of staying in the uterus.

These decisions can be difficult. You and your healthcare professional will make the decision together after discussing the fetus’s condition and the risks and benefits of waiting to deliver versus early delivery.

Delivery decisions are based on the cause of the FGR (if known), gestational age, and results of tests for fetal well-being. Here are the current guidelines, presuming that you do not have preeclampsia or other issues with your health:

• 38 to 39 weeks if testing shows the fetus is doing well.

• By or before 37 weeks if test results show an increased risk of complications. The higher the risks of complications, the earlier delivery may be recommended.

If delivery before 34 weeks is likely, or if you are between 34 and 37 weeks and there is a chance that you may deliver in the next 7 days, you may be given medications called corticosteroids. Corticosteroids help the fetus’s lungs and other organs mature and may improve the outcome if your baby is born preterm.