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(Large for Gestational Age; LGA)

Pronounced: mak-row-SOHM-ee-uh

En Español (Spanish Version)


Macrosomia is a condition in which a fetus is abnormally large. Babies with fetal macrosomia are born at a weight of at least 8 pounds, 13 ounces or more. The average birth weight for babies is about 7 pounds.

Most babies with macrosomia are born full-term, but some may be born pre-term. Babies born with macrosomia are more likely to experience low blood sugar, respiratory distress, and jaundice . They are also at an increased risk of birth defects.

Jaundice Baby

Jaundice Baby

© 2008 Nucleus Medical Art, Inc.

Macrosomia occurs in more than 10% of all pregnancies in the United States. Complications include a greater risk of Cesarean delivery , damage to the birth canal, and damage to the fetus if delivered vaginally.


The most common cause of fetal macrosomia is diabetes in the mother.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

The following factors increase your chance of giving birth to a baby with macrosomia:

  • Mother having diabetes
  • Mother having gestational diabetes
  • Mother and/or father of large size
  • Excessive weight gain by the mother during pregnancy

Signs and Symptoms

Signs include:

  • Birth weight of at least 8 pounds, 13 ounces to ten pounds (4,000- 4,500 grams) or higher


Your doctor will ask about your symptoms and medical history, and perform a physical and pelvic examination. An ultrasound will be performed to determine the size of the baby.

Your doctor will estimate the birth weight, and evaluate any dangers present for the mother and/or fetus.

If the fetal macrosomia is significant enough to cause potential harm during a vaginal delivery, a Cesarean delivery may be scheduled.

Ultrasound of Fetus

Fetal Ultrasound

© 2008 Nucleus Medical Art, Inc.


Talk with your doctor about the best treatment plan for you. Treatment options include:

Cesarean Delivery

Recommended for fetuses 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.


Macrosomia may not always be prevented, but the mother maintaining a healthy weight throughout the pregnancy can help prevent a large fetus.

For pregnant women with diabetes, precise control of blood sugar during pregnancy is extremely important to prevent macrosomia.

Proper prenatal care can also help diagnose any health conditions in the mother that could cause harm to the fetus. Early diagnosis of macrosomia can prevent complications during delivery.


The American College of Obstetricians and Gynecologists

National Institute of Child Health & Human Development

United States Centers for Disease Control and Prevention


British Columbia Ministry of Health

The Society of Obstetricians and Gynaecologists of Canada


Heiskanen N, Raatikainen K, Heinonen S. Fetal macrosomia—a continuing obstetric challenge. Biology of the Neonate . 2006;90(2):98-103. Epub 2006 Mar 16. Available at: . Accessed July 2, 2007.

The references below are cited on the following website: Zamorski MA, Biggs WS. Management of suspected fetal macrosomia. American Family Physician website. Available at: .
Berard J, Dufour P, Vinatier D, Subtil D, Vanderstichele S, Monnier JC, et al. Fetal macrosomia: risk factors and outcome. A study of the outcome concerning 100 cases >4500 g. Eur J Obstet Gynecol Reprod Biol . 1998;77:51-9.
Gregory KD, Henry OA, Ramicone E, Chan LS, Platt LD. Maternal and infant complications in high and normal weight infants by method of delivery. Obstet Gynecol . 1998;92:507-13.
Irion O, Boulvain M. Induction of labour for suspected fetal macrosomia. Cochrane Database Syst Rev . 2000.
Langer O, Berkus MD, Huff RW, Samueloff A. Shoulder dystocia: should the fetus weighing greater than or equal to 4000 grams be delivered by cesarean section? Am J Obstet Gynecol . 1991;165:831-7.
Parks DG, Ziel HK. Macrosomia. A proposed indication for primary cesarean section. Obstet Gynecol . 1978;52:407-9.

Last reviewed April 2008 by Ganson Purcell Jr., MD, FACOG, FACPE

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.

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