The effects of aerobic exercise on markers of maternal metabolism during pregnancy

Background Optimal maternal metabolism during pregnancy is essential for healthy fetal growth and development. Chronic exercise is shown to positively affect metabolism, predominantly demonstrated in nonpregnant populations. Objective To determine the effects of aerobic exercise on maternal metabolic biomarkers during pregnancy, with expected lower levels of glucose, insulin, and lipids among exercise-trained pregnant women. Methods Secondary data analyses were performed using data from two, longitudinal prenatal exercise intervention studies (ENHANCED by MOM and GESTAFIT). Exercisers completed 150 min of weekly moderate-intensity exercise during pregnancy (24+ weeks) while nonexercisers attended stretching sessions. Pregnant women were 31-33 years of age, predominantly non-Hispanic white, and "normal weight" body mass index. At 16 and 36 weeks of gestation, fasting blood samples were collected via fingerstick and venipuncture. Maternal glucose, insulin, insulin resistance (HOMA-IR), total cholesterol (TC), low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides (TG) were analyzed. ANCOVA analyses were performed to evaluate the effects of aerobic exercise on markers of maternal metabolism in late pregnancy, controlling for baseline levels. Results Our sample included 12 aerobic exercisers and 54 nonexercising control groups. Significant between-groups differences at 16 weeks of gestation were found for TG (92.3 vs. 121.2 mg/dl,p= .04), TC (186.8 vs. 219.6 mg/dl,p= .002), and LDL (104.1 vs. 128.8 mg/dl,p= .002). Aerobic-trained pregnant women exhibited lower insulin levels in late pregnancy (beta= -2.6 mu IU/ml, 95% CI:-4.2, -0.95,p= .002) and a reduced increase in insulin levels from 16 to 36 week of gestation (beta= -2.3 mu IU/ml, 95% CI: -4.4, -0.2,p= .034) compared with nonexercising pregnant women. No statistically significant effects were observed for maternal HOMA-IR, TC, LDL, HDL, TC:HDL, and TG in late pregnancy. Conclusions The observations of this study demonstrate that prenatal exercise may positively affect maternal insulin, with aerobic-trained pregnant women exhibiting lower insulin levels in late pregnancy. Additionally, we found no appreciable effects of prenatal exercise on maternal lipids in late pregnancy.