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(Large for Gestational Age; LGA)
  • Definition

    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.
    Jaundice Baby
    Jaundice Baby
    Copyright © Nucleus Medical Media, Inc.
  • Causes

    The most common cause of macrosomia is diabetes in the mother during pregnancy.
  • Risk Factors

    Factors that may increase your chance of giving birth to a baby with macrosomia include:
    • Mother having diabetes
    • Mother having gestational diabetes
    • Mother is obese
    • Mother and/or father of large size
    • Excessive weight gain by the mother during pregnancy
  • Signs and Symptoms

    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.
  • Diagnosis

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

    Talk with your doctor about the best treatment plan for you. Treatment options include:
    Cesarean Delivery
    Recommended for babies too large to be safely delivered through the birth canal.
    Feeding babies with macrosomia soon after birth is important to prevent low blood sugar in the baby.
    Feeding babies with macrosomia soon after birth is important to prevent low blood sugar in the baby.
  • Prevention

    To help prevent macrosomia:
    • Maintain a healthy weight throughout pregnancy
    • Exercise as advised by your doctor
    • Control blood sugar if you have diabetes
    • Receive prenatal care to diagnose problems early and prevent complications

    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: 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 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.

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