Maternal and neonatal complications of fetal macrosomia: cohort study.

Objective: To estimate the risks of maternal and neonatal complications in pregnancies with macrosomia.

Methods: This was a retrospective cohort study conducted at a large maternity unit in the UK between January 2009 and December 2016. The incidence of maternal and neonatal complications in pregnancies with macrosomia, defined as birth weight (BW) > 4000 g, and in those with severe macrosomia, defined as BW > 4500 g, was compared with that in pregnancies with normal BW (2500-4000 g). Regression analysis was performed to determine odds ratios (ORs) for complications in macrosomic pregnancies compared to those with normal BW.

Results: The study population of 35 548 pregnancies included 4522 (12.7%) with macrosomia, of which 643 (1.8%) had severe macrosomia, and 31 026 (87.3%) with normal BW. In the macrosomia group, the adjusted OR was 3.1 (95% CI, 2.6-3.6) for Cesarean section for failure to progress, 2.4 (95% CI, 2.0-3.0) for severe postpartum hemorrhage, 2.3 (95% CI, 1.9-2.8) for obstetric anal sphincter injury, 10.4 (95% CI, 8.6-12.6) for shoulder dystocia, 28.5 (95% CI, 8.9-90.7) for obstetric brachial plexus injury, 32.3 (95% CI, 3.8-278.2) for birth fractures and 4.4 (95% CI, 2.2-8.8) for hypoxic-ischemic encephalopathy. The respective values in pregnancies with severe macrosomia were 4.3 (95% CI, 3.1-6.1), 2.9 (95% CI, 1.9-4.4), 3.1 (95% CI, 1.9-5.1), 28.7 (95% CI, 20.8-39.8), 73.9 (95% CI, 15.1-363.2), 87.2 (95% CI, 7.7-985.0) and 13.8 (95% CI, 5.2-36.8).

Conclusion: Macrosomia is associated with serious adverse perinatal outcomes. This study provides accurate estimates of risks to aid in pregnancy management. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.