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Study: No Benefit With Early GDM Screening in Obese Women

LAS VEGAS — Early screening for gestational diabetes was not linked with a decrease in the risk of adverse perinatal outcomes in a cohort of obese women, a researcher said here.

There was no difference in the incidence of the primary outcome, which included cesarean delivery, macrosomia, and pregnancy-induced hypertension, among a group of obese pregnant women screened at 14 to 20 weeks gestation compared with those who received routine screening at 24 to 28 weeks (56.9% vs 50.9%, respectively, P=0.07), reported Lorie M. Harper, MD, of the University of Alabama at Birmingham.

Obesity now complicates about one-third of pregnancies, increasing the risk for gestational diabetes in over 1 million pregnancies each year, which in turn increases the risk for a multitude of perinatal complications, she noted at a presentation at the Society for Maternal-Fetal Medicine’s annual meeting.

Obesity is an indication to screen for gestational diabetes at the first prenatal visit, according to the American College of Obstetricians and Gynecologists, but Harper said that these recommendations are mostly based on “expert opinion,” with prior retrospective cohort studies actually demonstrating worse outcomes in early screened women.

Researchers performed a randomized controlled trial at two centers from June 2013 to January 2018. Participants included women with a BMI ≥30, who presented for care at <20 weeks. They were randomized to early screening at 14-20 weeks gestation, which was repeated at 24-28 weeks if the patient did not have gestational diabetes at the time of early screening.

For both early and routine screening, patients received a 50-g, 1-hour glucose tolerance test, followed by a 100-g 3-hour glucose tolerance test if their first score was ≥135. Gestational diabetes was diagnosed according to Carpenter-Coustan criteria, and treatment was initiated. Both groups also had HbA1c measurements at 14-20 weeks, and diabetes was diagnosed if HbA1c was ≥6.5%.

The primary outcome was a composite of several adverse neonatal outcomes, including primary C-section delivery, macrosomia (>4,000 g), pregnancy-induced hypertension, shoulder dystocia, neonatal hypoglycemia, and neonatal hyperbilirubinemia.

There were 455 women randomized to the early screen group and 458 to the routine screen group. Overall incidence of gestational diabetes was 13.0% (with 15.2% in the early group and 12.0% in the routine group). Patients were about age 27, over 60% were black, a quarter were Hispanic, and nearly all were on Medicaid. There were no significant differences in other baseline characteristics, such as HbA1c at 14-20 weeks, BMI, or hypertension.

Secondary outcomes examined individual aspects of the primary outcome, and found no differences between groups, with the exception of insulin use, which was higher in the early group.

Loralei Thornburg, MD, of the University of Rochester in New York, told MedPage Today that the findings were surprising, but also pointed out that they were likely limited to potential medical conditions for women with gestational diabetes, not women with type 2 diabetes.

“They were not able to address issues that real [women with type 2 diabetes] would have, such as increased risk of fetal cardiac disease and increased risk of fetal demise, because the population was too small,” said Thornburg, who was not involved in the study. “A portion of this early screening group are probably [women with type 2 diabetes] and you’re just catching them in pregnancy.”

When Harper and colleagues examined the results within women with gestational diabetes only, gestational age at delivery was associated with significantly lower gestational age (36.7 weeks vs 38.7 weeks, P=0.001).

Future directions for research could include performing a randomized double-blinded trial with a geographically, racially, and ethnically diverse cohort, Harper said. Thornburg suggested another potential direction for early screening research as a tool for identifying women with diabetes.

“It would be nice to see if early screening is going to help us determine who’s then going to screen in [for diabetes] postpartum, and who should be referred for pre-diabetes or diabetes outside of pregnancy,” Thornburg said. “This could help us address long-term women’s outcomes.”

The study was supported by the National Institute of Child Health and Human Development and the University of Alabama at Birmingham.

Harper and co-authors disclosed no relevant relationships with industry.


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