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Overview
Fetal growth restriction occurs when a baby doesn’t grow at a normal rate while in the womb. This is also called intrauterine growth restriction. Babies with this condition weigh less than 90 percent of other babies at the same stage of development (gestational age).
Being smaller than average doesn’t necessarily mean your baby has fetal growth restriction. For example, babies can be smaller than average and healthy if their parents are small in stature.
Depending on what’s causing it, fetal growth restriction can occur early or late in pregnancy.
Causes and Risk Factors
Many factors can cause fetal growth restriction. Often, we’re unable to determine an exact cause. There are several known risk factors.
Placenta problems
The placenta provides oxygen and nutrients to your growing baby. If the placenta doesn’t develop normally or attach properly to the wall of the uterus, it can’t function well.
Infection
Some infections can pass through the placenta from mother to baby. Examples include toxoplasmosis (infection from a parasite that causes ongoing muscle pain and fever) and cytomegalovirus (a type of herpes virus).
Maternal medical conditions
Conditions in the mother that can cause fetal growth restriction include:
- High blood pressure
- Diabetes
- Heart disease
- Chronic kidney disease
Birth defects or genetic conditions
Unborn babies with developmental abnormalities in their heart or intestines, or with Down syndrome or other genetic conditions can be at risk for growth restriction.
Poor maternal nutrition
Very poor or limited nourishment during pregnancy can affect the baby.
Carrying multiple babies
Pregnancies with more than one baby (twins, triplets, and other multiples) can affect each baby’s growth.
Maternal lifestyle behaviors
The baby’s growth can be restricted if the mother smokes, drinks alcohol, or uses drugs.
Symptoms and Diagnosis
We use these methods to diagnose fetal growth restriction.
Uterine fundal height
We estimate your baby’s growth by measuring from your pubic bone to the top of your uterus.
Ultrasound
If the uterine fundal height is lower than normal for your baby’s gestational age, we can perform an ultrasound. We’ll measure your baby’s head, belly (abdomen) and limbs to estimate your baby’s size. We then compare your baby’s size to others on a growth chart.
We may also recommend additional tests to try to understand the cause of your baby’s growth restriction.
Babies with fetal growth restriction need to be monitored closely due to a small risk of stillbirth (when a baby dies before birth).
We can use these monitoring methods.
Ultrasound
An ultrasound helps us track your baby’s growth and blood flow through key blood vessels. It will be recommended every 1 to 2 weeks depending on your baby’s size.
Nonstress testing (NST)
This measures your baby’s heart rate usually for 20 to 30 minutes. We will:
- Place an ultrasound device on your belly.
- Check whether your baby’s heart beats faster when they’re moving.
We may recommend testing once or twice a week.
Kick counts
We may ask you to track the number of your baby’s kicks. This also gives you a way to monitor your baby’s well-being between prenatal visits.
Possible Complications
Babies with growth restriction are more likely to have health problems before, during, and after birth. The level of a baby’s risk for health problems depends on what caused the growth restriction and how severe it is, as well as whether:
- The restriction occurred early or later in pregnancy.
- The baby is born near their due date, or prematurely (preterm birth).
Health problems in the baby that can occur before birth include:
- Dying before being born (stillbirth)
- Abnormal heartbeat during labor, which causes a related higher risk for cesarean delivery (C-section)
- Breathing and feeding problems
- Low blood sugar level (hypoglycemia)
- Reduced ability to fight infection
- Difficulty maintaining normal body temperature
Babies with growth restriction who are otherwise healthy often catch up with children of their age. Some babies have long-term medical problems, however.
We’ll talk with you about possible risks based on your baby’s individual situation.
Treatment
Treatment for fetal growth restriction involves deciding on the best time to deliver the baby. Delivering the baby is the only way we can eliminate the risk of stillbirth.
Deciding when to deliver the baby is based on when in pregnancy growth restriction occurs and how severe it is.
We also treat any medical condition that can cause growth restriction.
Prevention
You can avoid some of the factors that cause fetal growth restriction. Follow these recommendations to help your baby grow normally:
- Don’t smoke, drink alcohol, or use illegal drugs.
- Eat healthy foods.
- Get regular prenatal care.
Talk with your doctor before getting pregnant if you have a chronic medical condition, such as high blood pressure or diabetes.