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A baby who is small for gestational age (SGA) has a significantly lower weight than other babies of the same gestational age. Gestational age is the number of weeks into pregnancy.

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If parents have small stature, the baby may be small. These babies have normal uterine growth but are just small compared to others their age.

SGA also occurs if there are growth and development problems before birth. These may occur with:

  • Problems with the supply of nutrients and oxygen to the baby or a small uterus
  • Exposure to toxic substances or certain medications
  • Infections or chronic illness during pregnancy
  • Birth defects
  • Genetic syndromes

Risk Factors

Parents with small stature or prior birth of a SGA baby increase the risk of SGA.

Maternal factors that can affect a baby’s growth during pregnancy include:

Other factors that can affect baby’s growth include:

  • Pregnancy with more than 1 child
  • Birth defects
  • Genetic syndromes in the baby


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


A baby with SGA is often diagnosed before birth based on measurements taken of the mother’s abdomen, the mother’s weight, and size of the uterus (womb). If the measurement is low for the number of weeks of pregnancy, then 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.


Talk with your doctor about the best treatment plan for your baby. A baby with SGA is at higher risk for problems, such as difficulty feeding, blood sugar abnormalities, and breathing problems. Your baby’s health and development will be monitored closely.

Babies that have SGA due to lack of nutrition or oxygen may need treatment. Options include:

Before Delivery

Before your baby is born, the doctor may:

  • Monitor your baby’s growth progress closely
  • Deliver your baby early if the uterus is too small to allow your child to develop or there are problems with the mother’s health or the placenta that are affecting the babies growth
  • Treat or try to improve the treatment of any conditions that you have

After Delivery

Babies who are born with SGA may be weak and unable to feed properly or stay warm. Treatment may include:

  • Using warming beds or incubators
  • Providing tube feedings
  • Monitoring oxygen levels

Ongoing monitoring and treatment may be needed during childhood.


SGA due to family traits, syndromes, and uterine abnormalities cannot be prevented.

If you are thinking of becoming pregnant, taking a supplement containing folic acid may reduce the risk of having a small for gestational age baby.

To help reduce your baby’s chance of getting SGA due to nutrition and oxygen problems during birth, take these steps during pregnancy:

  • If you smoke, talk to your doctor about ways to quit.
  • If you use drugs or alcohol, ask your doctor to refer you to a treatment program that will help you stop.
  • Start prenatal care early and continue throughout pregnancy.
  • Keep any chronic condition under good control.


American Pregnancy Association 

Healthy Children—American Academy of Pediatrics 


Canadian Paediatric Society 

Health Canada 


Intrauterine growth restriction (IUGR); Small for gestational age (SGA). American Pregnancy Association website. Available at: Updated February 22, 2017. Accessed December 20, 2017.

Small for gestational age. Lucile Packard Children’s Hospital website. Available at: Accessed December 20, 2017.

Small for gestational age babies. Patient UK website. Available at: Updated October 21, 2016. Accessed December 20, 2017.

Small for gestational age introduction. The MAGIC Foundation website. Available at: Accessed December 20, 2017.

11/19/2013 DynaMed Plus Systematic Literature Surveillance.  : Roos N, Neovius M, et al. Perinatal outcomes after bariatric surgery: nationwide population based matched cohort study. BMJ 2013;347:f6460.

3/17/2015 DynaMed Plus Systematic Literature Surveillance.  : Hodgetts V, Morris R, et al. Effectiveness of folic acid supplementation in pregnancy on reducing the risk of small-for-gestational age neonates: a population study, systematic review and meta-analysis. BJOG. 2015 Mar;122(4):478-490.

7/7/2016 DynaMed Plus Systematic Literature Surveillance.  : Pamidi S, Marc I, et al. Maternal sleep-disordered breathing and the risk of delivering small for gestational age infants: a prospective cohort study. Thorax. 2016 Apr 15.

7/15/2016 DynaMed Plus Systematic Literature Surveillance.  : Saccone G, Berghella V, Sarno L, et al. Celiac disease and obstetric complications: a systematic review and metaanalysis. 2016;214(2):225-234.

Revision Information

  • Reviewer: EBSCO Medical Review Board Michael Woods MD FAAP
  • Review Date: 11/2018
  • Update Date: 07/16/2016