Abdominal adiposity and insulin resistance in early pregnancy.

Background: High pre-pregnancy body mass index is a known risk factor for gestational diabetes mellitus, but the contribution of abdominal adiposity to insulin resistance (IR) in pregnancy is not well understood. We assessed the association between abdominal adiposity in early pregnancy and IR.

Methods: We completed a prospective cohort study of 79 pregnant women. Visceral adipose tissue (VAT) depth was measured by ultrasonography at 11 to 14 weeks' gestation, at the time of routine fetal nuchal translucency assessment. A two-hour 75 g oral glucose tolerance test was subsequently completed at 16 to 22 weeks' gestation and IR was estimated by the homeostatic model assessment of insulin resistance (HOMA-IR) as well as by the insulin sensitivity index.

Results: After adjusting for maternal age, parity, ethnicity, and pre-pregnancy BMI, VAT depth explained 42% of the variance in HOMA-IR, which was slightly better than the variance in the multivariable model examining HOMA-IR and pre-pregnancy BMI (40%). For the insulin sensitivity index, the model variance values were 36% and 32%, respectively.

Conclusion: Measurement of maternal adipose tissue depth at the time of routine first-trimester ultrasonography may provide additional information about maternal IR, beyond pre-pregnancy BMI.