Macrosomia is a condition in which a baby is abnormally large before birth. The average birth weight for babies is about 7 pounds. Babies with macrosomia have a birth weight of at least 8 pounds, 13 ounces or more.
Macrosomia occurs in more than 10% of all pregnancies in the United States. It may lead to pregnancy complications such as a greater risk of cesarean delivery, damage to the birth canal, and injury to the baby during a vaginal delivery.
Babies born with macrosomia are more likely to have low blood sugar, respiratory distress, and jaundice.
The most common cause of macrosomia is diabetes in the mother during pregnancy.
Factors that may increase your chance of giving birth to a baby with macrosomia include:
The main symptom of macrosomia is a birthweight of at least 8 pounds, 13 ounces or more. This birthweight may be estimated during prenatal testing.
Your doctor will ask about your symptoms and medical history. A physical and pelvic examination will be done. An ultrasound can help determine the size of the baby before birth.
Your doctor will estimate the birth weight and evaluate any dangers for the mother and/or baby.
If the fetal macrosomia may cause potential harm during a vaginal delivery, a Cesarean delivery may be scheduled.
Talk with your doctor about the best treatment plan for you. Treatment options include:
Feeding babies with macrosomia soon after birth is important to prevent low blood sugar in the baby.
The American Congress of Obstetricians and Gynecologists
Centers for Disease Control and Prevention
British Columbia Ministry of Health
The Society of Obstetricians and Gynaecologists of Canada
Gestational diabetes mellitus (GDM). EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 22, 2013. Accessed April 1, 2013.
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's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: 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 May 2015 by Andrea Chisholm, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.