Maternal body adiposity changes during pregnancy and association with cardiometabolic status and adverse outcomes in a randomized nutrition+exercise intervention trial

Abstract

Rationale & Background: Gaining excessive adiposity in pregnancy is associated with altered cardiometabolic profile and adverse pregnancy outcomes. Lifestyle interventions may reduce excess weight gain, but the effect on fat gain is unclear. Our study explored this question by 1) comparing measures of body fat (BF) by bioelectrical impedance analysis (BIA) and 4-site skinfold thickness (SFT); 2) assessing the impact of a nutrition+exercise intervention on adiposity changes; 3) elucidating associations between adiposity changes and cardiometabolic biomarkers and adverse pregnancy outcomes. Study Design: Participants randomized to receive a high dairy protein diet and exercise program (intervention) or standard care (control) in the Be Healthy in Pregnancy RCT (NCT 01689961) had adiposity measured at 12-17, 26-28, and 36-38 weeks gestation by BIA (%BF) and SFT (sum and %BF), and at 6 months postpartum also by DXA. Fasted blood samples collected at 12-17 and 36-38 weeks gestation were analyzed for glucose, lipid profile, insulin, leptin, adiponectin, and CRP. Pregnancy outcomes were abstracted from medical charts.

Results: In 181 participants, BIA %BF and SFT %BF had good agreement in early pregnancy and postpartum, but low agreement in late pregnancy. Adiposity changes across pregnancy were similar between study arms but were greater in normal weight compared to overweight women. Insulin and leptin were negatively associated with change in SFT (sum and %BF). Triglycerides were negatively associated with change in BIA %BF, while HDL was positively associated. Neither caesarean section nor operative vaginal delivery were associated with adiposity change.

Conclusion: Adiposity measured by sum of SFT and BIA %BF increased across pregnancy but was not influenced by the diet+exercise intervention. Associations of adiposity change with cardiometabolic biomarkers varied between measurement tools. The lack of adiposity measurement tools appropriate across pregnancy and in clinical settings presents a concern for assessing clinical responses to adiposity change across pregnancy.