Overview
The term “fetal macrosomia” is used to describe a newborn who’s much larger than average.
A baby who is diagnosed as having fetal macrosomia weighs more than 8 pounds, 13 ounces (4,000 grams), regardless of his or her gestational age. About 9% of babies worldwide weigh more than 8 pounds, 13 ounces.
Risks associated with fetal macrosomia increase greatly when birth weight is more than 9 pounds, 15 ounces (4,500 grams).
Fetal macrosomia may complicate vaginal delivery and can put the baby at risk of injury during birth. Fetal macrosomia also puts the baby at increased risk of health problems after birth.
Symptoms
Fetal macrosomia can be difficult to detect and diagnose during pregnancy. Signs and symptoms include:
- Large fundal height. During prenatal visits, your health care provider might measure your fundal height — the distance from the top of your uterus to your pubic bone. A larger than expected fundal height could be a sign of fetal macrosomia.
- Excessive amniotic fluid (polyhydramnios). Having too much amniotic fluid — the fluid that surrounds and protects a baby during pregnancy — might be a sign that your baby is larger than average.The amount of amniotic fluid reflects your baby’s urine output, and a larger baby produces more urine. Some conditions that cause a baby to be larger might also increase his or her urine output.
Fundal height
Fundal height is the distance from the pubic bone to the top of the uterus measured in centimeters. After 24 weeks of pregnancy, fundal height often matches the number of weeks you’ve been pregnant.
Polyhydramnios
In polyhydramnios, excessive amniotic fluid accumulates in the uterus during pregnancy. Mild cases of polyhydramnios may go away on their own. Severe cases may require treatment.
