Small for Gestational Age



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 pregnant people who have had a prior SGA baby.

During pregnancy, problems in the pregnant person 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
  • Some infections
  • Taking some medicines

Other things that raise the risk are:

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



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


A baby with SGA is often diagnosed before birth. A physical exam will be done on the pregnant person. Measurements will be taken of their 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.



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

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

Before Delivery

The doctor may:

  • Watch the baby’s growth
  • Deliver the baby early if growth problems are very bad
  • Treat health problems in the pregnant person

After Delivery

Babies who are born with SGA may be weak. They may not be able to feed enough or stay warm. Treatment may include:

  • Putting them in warming beds or incubators
  • Giving tube feedings
  • Checking oxygen levels

A baby with SGA needs to be watched and treated as they grow during childhood.


SGA cannot be prevented when it is due to genes or problems with the uterus.

Pregnant people may reduce their 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

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.