Definition

A baby who is small for gestational age (SGA) has a lower weight than normal for the number of weeks of pregnancy. Sometimes this raises the risk of early birth, low birth weight, miscarriage and other problems.

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Causes

SGA may be caused by growth problems before birth. This can be due to:

• Lack of nutrients and oxygen to the baby
• A small uterus
• Exposure to certain substances
• Infections or long term illnesses during pregnancy
• Birth defects
• Problems with genes

Sometimes a baby is small because the parents are small. These babies have normal growth. They are just small compared to others their age.

Risk Factors

SGA is more common in mothers who have had a prior SGA baby.

During pregnancy, problems in the mother can raise the risk. They include:

• High blood pressure
• Smoking, using street drugs or drinking alcohol
• Problems with the placenta, such as placental abruption or placenta previa
• Poor nutrition and not taking folic acid
• Long term medical problems, such as kidney failure, gestational diabetes, asthma, systemic lupus erythematosus, celiac disease, or anemia
• Certain infections
• Taking certain medicines

Other things that raise the risk are:

• Pregnancy with more than one fetus—such as twins or triplets
• Birth defects or genetic problems in the baby

Symptoms

Symptoms of SGA are a weight that is in the lowest 10% of babies with the same gestational age.

Diagnosis

A baby with SGA is often diagnosed before birth. A physical exam will be done on the mother. Measurements will be taken of the mother’s belly, weight, and uterus (womb). They are based on the number of weeks of pregnancy. If the measurements are low, the baby may be smaller than average. SGA may also be diagnosed at birth based on the baby’s weight and height.

Images may be taken during pregnancy with an ultrasound.

Treatment

The goal is to watch for and treat problems in the mother and baby.

Babies that have SGA from lack of nutrition or oxygen may need treatment. Options are:

Prevention

SGA cannot be prevented when due to genes, syndromes, or problems with the uterus.

Otherwise, pregnant women may reduce the baby's risk of SGA by:

• Taking folic acid
• Not smoking, drinking alcohol, or using drugs
• Having early and ongoing prenatal care
• Getting care for long term health problems