Increased fetal size in gestational diabetes after week 20 of pregnancy

1. Study findings suggest gestational diabetes is associated with larger fetal size starting at week 20, and that efforts to mitigate associated fetal growth should start between 24-28 gestational weeks.

Evidence Rating: 1 (Excellent)

Maternal glucose concentrations have been found to be positively associated with birth weight, with mothers with gestational diabetes more likely to give birth to children who are large-for-gestational age and at increased risk for later development of obesity and diabetes. Prior literature has largely focused on late pregnancy however, and no studies to date have attempted to precisely identify the gestational week when fetal growth begins to differ by maternal glycemic status. In this prospective cohort study, 2458 pregnant women were enrolled from 2009 to 2013 in the NICHD Fetal Growth Studies-Singletons study to address this gap. Specifically, women were enrolled at gestational weeks 8-13 and assigned to ultrasonogram schedules that would capture weekly fetal growth. Of the 2458 participants, 105 (4.4%) had gestational diabetes, 118 (4.8%) had impaired glucose tolerance, and 2020 (82.2%) had normal glucose tolerance. Compared to the NGT cohort, fetal weight of mothers with gestational diabetes was larger at starting from week 20 and statistically significant at weeks 28-40 (at week 37: 3061g [95% CI 2967-2962] vs. 2943g [2924-2962]). Maternal glucose concentrations at weeks 10-14 were additionally significantly associated with a larger estimated fetal weight from week 27 through term. Overall, this study is the first to propose a set week by which estimated fetal weight begins to differ between mothers with gestational diabetes from control. If these estimates are indeed accurate, this further suggests an importance of monitoring glycemic status to abate fetal growth prior to 24-28 weeks of gestation.

Click to read the study in Lancet Diabetes & Endocrinology

Image: PD

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