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DALLAS -- Antenatal steroids for late preterm deliveries was associated with an increased risk of neonatal hypoglycemia compared with early preterm deliveries, researchers said here.

There was nearly a two-fold increased risk in neonatal hypoglycemia for late preterm deliveries versus early term (adjusted RR 1.91, 95% CI 1.20-2.85), reported Kristina E. Sondegroth, MD, of Washington University in St. Louis, and colleagues, in a at the Society for Maternal-Fetal Medicine (SMFM) Annual Pregnancy Meeting.

It is the latest development in research surrounding the use of antenatal steroids in late preterm birth. Both SMFM and the American College of Obstetricians and Gynecologists (ACOG) formally recommended the use of antenatal steroids in April 2016 after a trial presented at the 2016 SMFM meeting, and published in the New England Journal of Medicine, found an improvement in neonatal outcomes with their use compared to placebo.

But a NEJM accompanying noted a significant difference in neonatal hypoglycemia among infants who received antenatal steroids, and neonatal hypoglycemia has been linked to developmental delays in preterm infants.

Sondegroth noted that there has been "conflicting data" on the risk of neonatal hypoglycemia after antenatal steroids in late preterm, with "inconclusive" evidence due to wide heterogeneity in design and definition of neonatal hypoglycemia.

Her group hypothesized that late preterm (defined as 34-36 weeks) steroids would be linked to a higher risk of neonatal hypoglycemia than early preterm (defined as 23 to 33 weeks) steroids, but that maternal hyperglycemia may mediate this risk.

The prospective cohort study measured maternal blood glucose levels at 24 and 48 hours after the first dose, as well as at delivery, and neonatal glucose levels within an hour of delivery. Neonatal hypoglycemia was defined as (blood glucose (<40 mg/dL). Sondegroth noted that they did not do continuous glucose monitoring, instead choosing a "pragmatic time point" to measure glucose levels.

There were 265 patients in the early preterm group and 103 in the late preterm group, and the median age for both groups was around age 28. A little under half of each group were black. There were no significant differences between groups except gestational age at dose 1 and delivery.

Overall, a significantly higher portion of infants in the late preterm group had neonatal hypoglycemia (24.3% vs 13.2% in early preterm group, P=0.01). This risk remained higher in a time-to-event analysis (adjusted HR 4.41, 95% CI 2.15-9.05).

But there was no significant difference in maternal glucose levels between infants with neonatal hypoglycemia and those without, at any of the three time points. Moreover, there was no correlation between maternal glucose and neonatal glucose.

"The lack of relation to maternal hypoglycemia suggests that it is related to direct affects on fetus glucose metabolism rather than on higher transmission of glucose from the mother," Loralei Thornburg, MD, of the University of Rochester Medical Center in New York, told 番茄社区app.

"Further information on reasons for preterm delivery, and other maternal and fetal characteristics, may shed further light on factors involved in neonatal hypoglycemia in late preterm birth steroid administration," said Thornburg, who was not involved in the study.

Among late preterm infants only (25 with hypoglycemia, 78 with no hypoglycemia), there was also no significant difference in neonatal outcomes, such as hospital days, hyperbilirubinemia, or hypothermia.

Sondegroth said that these results indicate that "intensive control of maternal hyperglycemia may not be needed to reduce the risk" of neonatal hypoglycemia. She hypothesized that other mechanisms, such as fetal adrenal suppression, may be involved.