Nondiabetic Fetal Macrosomia: Causes, Outcomes, and Clinical Management.

Importance: Fetal macrosomia (FM) is common in clinical practice and carries increased risk of adverse maternal and neonatal health outcomes. Maternal diabetes mellitus (DM) is a well-known cause of macrosomia with significant research and guidelines focusing on macrosomia in this population. Less is known about causes, prevention, and clinical management for suspected FM in individuals without diabetes.

Objective: The objective of this review is to describe the risk factors associated with nondiabetic FM, review risks associated with macrosomia in pregnancy, and potential treatment considerations for this condition.

Evidence acquisition: Original research articles, review articles, and guidelines on macrosomia were reviewed.

Results: Risk factors for macrosomia in patients without DM include previous delivery of an infant with macrosomia, excessive pregnancy weight gain, and obesity. Maternal complications of FM include higher rates of cesarean delivery, postpartum hemorrhage, and vaginal laceration. Fetal complications include shoulder dystocia, decreased Apgar scores, and increased risk of childhood obesity. Exercise during pregnancy has been shown to reduce the risk of FM. Induction of labor prior to 39 weeks is not recommended in the setting of suspected macrosomia as there is a lack of adequate evidence to support that this decreases adverse neonatal or maternal outcomes. In addition, elective cesarean delivery for suspected macrosomia is not recommended to be considered unless estimated fetal weight is greater than 5000 g in the absence of DM.

Conclusions and relevance: Delivery of an infant with macrosomia in patients without DM has increased maternal and fetal risks. Predicting infants who will meet criteria for macrosomia is challenging. More research is needed to identify ways to accurately estimate fetal weight, interventions to prevent macrosomia, and additional ways to mitigate risk in patients without DM who have suspected FM.