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
© 2009 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
© 2009 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.