Central fat accretion and insulin sensitivity: differential relationships in parous and nulliparous women

Childbearing is associated with a disproportionate accumulation of visceral fat and an increased risk of metabolic disease. However, it is unknown whether the visceral fat accretion associated with pregnancy modifies a woman's risk for metabolic disease. The purpose of this study was to test whether the association between abdominal fat and insulin sensitivity differs by parity status in healthy overweight women.

Intra-abdominal adipose tissue (IAAT) via CT, body composition by DXA, insulin sensitivity via intravenous glucose tolerance test and minimal model (S_I), HOMA-IR, and cardiorespiratory fitness (VO_2max) were assessed in 212 non-diabetic, premenopausal, overweight non-Hispanic white and African-American women.

Nulliparous women (n=98) were younger, had less IAAT and higher VO_2max, but similar S_I, HOMA-IR and leg fat, compared to parous (n=114). In nulliparous women, IAAT was negatively associated with S_I, controlling for age, race and body fat mass (r=-0.40, P<0.001), but this relationship was attenuated in parous women (r=-0.15, P=0.16). In multiple linear regression analysis, leg fat and IAAT were significant predictors of S_I in nulliparous, but not parous women.

Results suggest that greater IAAT in parous women does not lead to greater insulin resistance; rather, transient insulin resistance during pregnancy may encourage intra-abdominal fat accumulation that is metabolically benign. This underscores the need to consider parity when assessing cardiometabolic risk.