Health Library



Macrosomia is when a baby is larger than normal before birth. Most babies are about 7 pounds (3.17 kilograms). Babies with this health problem are 8 pounds, 13 ounces (3.99 kilograms) or more.


The most common cause is diabetes in the mother during pregnancy.

Risk Factors

Things that may raise the risk are:

  • Mother having diabetes
  • Mother having gestational diabetes
  • Mother is obese
  • Mother and/or father of large size
  • Too much weight gain by the mother during pregnancy


The main sign is a predicted birthweight of at least 8 pounds, 13 ounces or more.


The doctor will ask about your symptoms and health history. A physical and pelvic exam will be done.

Your doctor will estimate the birth weight and review any dangers for the mother and baby. Pictures may be taken. This can be done with ultrasound .

Giving birth through the birth canal may cause harm to the mother and baby. A Cesarean delivery (C-section) may be scheduled.

Ultrasound of Fetus
Fetal Ultrasound
Copyright © Nucleus Medical Media, Inc.


Talk with your doctor about the best plan for you. You may have:


Your baby may be too large to be delivered safely through the birth canal. The doctor may advise a C-section.

Care After Birth

After your baby is born, the doctor will check for signs of low blood sugar.


To help prevent this health problem:

  • Stay at a healthy weight throughout the pregnancy.
  • Exercise as advised by your doctor.
  • Control blood sugar if you have diabetes.
  • Ask your doctor about testing for gestational diabetes.
  • Get early prenatal care.


The American Congress of Obstetricians and Gynecologists

Centers for Disease Control and Prevention

Canadian Resources

The Canadian Women's Health Network

The Society of Obstetricians and Gynaecologists of Canada (SOGC)


Gestational diabetes mellitus (GDM). EBSCO DynaMed Plus website. Available at: . Updated July 13, 2018. Accessed August 7, 2018.

Heiskanen N, Raatikainen K, Heinonen S. Fetal macrosomia—a continuing obstetric challenge. Biology of the Neonate. 2006;90(2):98-103.

Zamorski MA, Biggs WS. Management of suspected fetal macrosomia. Am Fam Physician. 2001;15;63(2):302–307.

6/16/2015: DynaMed Plus Systematic Literature Surveillance : Wiebe HW, Boulé NG, Chari R, Davenport MH. The effect of supervised prenatal exercise on fetal growth: a meta-analysis. Obstet Gynecol. 2015 May;125(5):1185-1194.