Association Between Type of Screening for Gestational Diabetes Mellitus and Cesarean Delivery.

OBJECTIVE: To compare maternal and neonatal outcomes using two different testing strategies for gestational diabetes mellitus (GDM) diagnosis: the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) and Carpenter-Coustan approaches. Specifically, we wanted to compare the rates of cesarean delivery between the two epochs.

METHODS: This was a retrospective cohort study of women with a singleton pregnancy delivering at 37 0/7 weeks of gestation or greater, between 2010 and 2015, in a single tertiary care center. The IADPSG testing was used for GDM diagnosis from December 2010 until July 2013 when institutional guidelines changed to Carpenter-Coustan testing. Maternal and neonatal outcomes were compared between these two different epochs using bivariable and multivariable analyses. The primary outcome was the frequency of cesarean delivery.

RESULTS: The analysis included a total of 23,509 women: 14,074 (60%) from the IADPSG epoch and 9,435 (40%) from the Carpenter-Coustan epoch. The incidence of GDM diagnosis was higher using the IADPSG compared with Carpenter-Coustan criteria (8.3% compared with 7.5%, P=.042). The total (27.0% compared with 25.5% P=.022) as well as primary cesarean delivery rates (19.1% compared with 18.0%, P=.041) were higher during the IADPSG epoch. The rates of total (39.1% compared with 37.5%, P=.594) and primary (27.3% compared with 27.0%, P=.903) cesarean delivery among women with GDM did not differ between the two epochs. Secondary outcomes of shoulder dystocia (2.5% compared with 2.1%, P=.043) and neonatal intensive care unit admission (3.2% compared with 2.0%, P<.001) also were significantly higher in women screened during the IADPSG epoch, whereas hypertensive disease of pregnancy (6.9% compared with 7.7%, P=.018) was less frequent during the IADPSG epoch. These findings persisted after adjusting for potential confounding factors.

CONCLUSION: Compared with testing using the Carpenter-Coustan criteria, the IADPSG criteria for diagnosis of GDM were associated with higher rates of GDM, cesarean delivery, shoulder dystocia, and neonatal intensive care unit admission. Obstetric care provider knowledge of GDM diagnosis might have affected decision-making regarding the route of delivery.