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.

Causes

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

Risk Factors

Things that may raise the risk are:

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

Symptoms

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

Diagnosis

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

Pictures may be taken to estimate the birth weight. This can be done with ultrasound.

Ultrasound of Fetus

Treatment

The goal of treatment is to safely deliver the baby. The baby may be too large to be delivered through the birth canal. A Cesarean delivery (C-section) may be done.

Prevention

To lower the risk of this problem:

Get early prenatal care.
Maintain a healthy weight during pregnancy.
Manage diabetes.

RESOURCES:

American Congress of Obstetricians and Gynecologists
http://www.acog.org

Centers for Disease Control and Prevention
http://www.cdc.gov

CANADIAN RESOURCES:

Women's Health Matters
https://www.womenshealthmatters.ca

Society of Obstetricians and Gynaecologists of Canada
http://sogc.org

References:

American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 190: Gestational Diabetes Mellitus. Obstet Gynecol. 2018 Feb;131(2):e49-e64, reaffirmed 2019.

Gestational diabetes mellitus (GDM). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/gestational-diabetes-mellitus-gdm. Updated July 13, 2018. Accessed August 7, 2018.

6/16/2015: DynaMed Systematic Literature Surveillance https://www.dynamed.com/condition/gestational-diabetes-mellitus-gdm: Wiebe HW, Boulé NG, et al. The effect of supervised prenatal exercise on fetal growth: a meta-analysis. Obstet Gynecol. 2015 May;125(5):1185-1194.

Last reviewed September 2020 by EBSCO Medical Review Board Elliot M. Levine, MD, FACOG
Last Updated: 4/27/2021

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