Large-for-Gestational-Age Ultrasound Diagnosis and Risk for Cesarean Delivery in Women With Gestational Diabetes Mellitus

OBJECTIVE:To assess the accuracy of a large-for-gestational-age (LGA) ultrasound diagnosis and the subsequent risk for cesarean delivery associated with ultrasound diagnosis of LGA among women with gestational diabetes mellitus.METHODS:This was a retrospective cohort study of 903 women with GDM who delivered after 36 weeks of gestation with an ultrasound-estimated fetal weight within 31 days of delivery. Delivery outcomes were compared between women with an ultrasound diagnosis of LGA and a non-LGA ultrasound diagnosis.RESULTS:Based on ultrasound assessments, we identified 248 women with an LGA fetus and 655 women with a non-LGA fetus. Among women with an LGA ultrasound diagnosis, 56 of 248 (22.6%) delivered an LGA neonate, whereas, of women with a non-LGA ultrasound diagnosis, 18 of 655 (2.8%) delivered an LGA neonate. Ultrasound diagnosis of LGA was associated with increased risk for cesarean delivery (adjusted odds ratio [OR] 3.13, 95% confidence interval [CI] 2.10-4.67, P<.001) after adjusting for relevant covariates. Stratified analyses demonstrated that ultrasound diagnosis of LGA was associated with an increased risk for cesarean delivery whether the birth weight was between 2,500 and 3,499 g (OR 2.82, 95% CI 1.62-4.84, P<.001) or between 3,500 and 4,500 g (OR 3.47, 95% CI 2.06-5.88, P<.001).CONCLUSION:Ultrasonography significantly overestimates the prevalence of LGA in women with gestational diabetes mellitus, and an ultrasound diagnosis of LGA is associated with an increased risk for cesarean delivery independent of birth weight.LEVEL OF EVIDENCE:II