Signs of excessive fetal growth emerge at 20 weeks in gestational diabetes
A cohort of women with gestational diabetes showed signs of larger estimated fetal weight beginning at 20 weeks when compared with pregnant women with normal glucose tolerance, with the association persisting through delivery, according to findings published in The Lancet Diabetes & Endocrinology.
“Infants born to mothers with gestational diabetes are more likely to be born large for gestational age, and to develop obesity and diabetes later in life, contributing to an intergenerational cycle of metabolic risk,” Cuilin Zhang, MD, PhD, MPH, a senior investigator in the epidemiology branch of the division of intramural population health research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the NIH in Bethesda, Maryland, and colleagues wrote in the study background. “However, the exact timing during gestation when fetal growth begins to deviate in relation to women’s glycemic status is not completely understood; the answer to this question could inform the optimal timing for screening and treatment of hyperglycemia during pregnancy.”
Zhang and colleagues analyzed data from 2,458 pregnant women without major chronic conditions at baseline who participated in the NICHD Fetal Growth Studies-Singletons cohort, which took place between 2009 and 2013 and included 12 centers throughout the U.S. Researchers randomly assigned women to one of four ultrasound schedules to assess fetal growth. Group A underwent ultrasounds at 16, 24, 30 and 34 weeks; group B at 18, 26, 31, 35 and 39 weeks; group C at 20, 28, 32 and 36 weeks; and group D at 22, 29, 33, 37 and 41 weeks. Gestational diabetes, impaired glucose tolerance and normal glucose tolerance were defined by medical record review; glucose was measured in a subsample of women at 10 to 14 weeks. Researchers used linear mixed models to model fetal growth trajectories.
Within the cohort, 107 (4.4%) had gestational diabetes, 118 (4.8%) had IGT and 2,020 (82.2%) had normal glucose tolerance.
Researchers found that gestational diabetes was associated with a larger estimated fetal weight that started at week 20, became significant at weeks 28 and persisted through term.
A fetus at 37 weeks’ gestation was on average 118 g larger in women with gestational diabetes compared with women with normal glucose tolerance (mean, 3,061 g vs. 2,943 g; adjusted P = .02). Researchers found that IGT was only marginally associated with overall estimated fetal weight trajectory (P = .06) but was associated with larger estimated fetal weight at 36 to 40 weeks.
Additionally, continuous glucose concentrations at 10 to 14 weeks’ gestation were associated with overall estimated fetal weight trajectory. Increasing tertiles of glucose corresponded with increasingly larger estimated fetal weight in late pregnancy, according to researchers, with the difference emerging at week 23 and becoming significant at 27 weeks.
“If confirmed, these findings show that it might be helpful to initiate efforts to monitor glycemic status to mitigate accelerated fetal growth before 24 to 28 weeks of gestation, when gestational diabetes is typically screened for,” the researchers wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.