Obesity During Pregnancy May Lead Directly to Fetal Overgrowth

Woman rests her hands atop her pregnant belly as she stands on a scale

Obesity during pregnancy may account for the higher risk of giving birth to an atypically large infant.

Photo: ThinkStock/adrian825

Obesity during pregnancy—independent of its health consequences such as diabetes—may account for the higher risk of giving birth to an atypically large infant, according to researchers at NIH. Their study appears in JAMA Pediatrics.

“Our results underscore the importance of attaining a healthy body weight before pregnancy,” said the study’s lead author Dr. Cuilin Zhang, a researcher in NICHD’s Division of Intramural Population Health Research. “They also suggest that clinicians should carefully monitor the pregnancies of all obese women, regardless of whether or not they have obesity-related health conditions.”

Macrosomia—large body size at birth—is common among children born to obese women, particularly those who have gestational diabetes (high blood sugar during pregnancy). Macrosomia increases the risk that an infant will experience bone fracture during delivery. It also increases the likelihood that the infant will need to be delivered by cesarean section.

Having a large infant also increases a mother’s risk for postpartum hemorrhage, or excessive bleeding at birth.

The authors pointed out that earlier studies have indicated that the higher risk of overgrowth seen in newborns of obese women may predispose these infants to obesity and cardiovascular disease later in life. They called for additional studies to follow the children born to obese women to determine what health issues they may face.