The Differential Effects of Prenatal Exercise Training Type on Maternal Glucose Metabolism: A Secondary Data Analysis of a Prospective Randomized Controlled Trial

Abstract

Gestational diabetes mellitus (GDM) complicates 10-12% of pregnancies worldwide and poses significant, immediate, and long-term health risks to both the mom and baby. Importantly, consistent research demonstrates participating in sufficient levels of exercise during pregnancy may effectively manage maternal glucose levels, thereby potentially decreasing the risk of GDM. Most of these studies however, restricted their investigations to exposing pregnant women only to aerobic exercise. Previous studies in non-pregnant populations showed various exercise training types, such as resistance and combined (resistance + aerobic) training, elicited positive, independent effects on glucose metabolism, yet similar effects in pregnant women are unclear. PURPOSE: To evaluate differential effects of prenatal exercise training types during mid-to-late pregnancy on maternal glucose metabolism. METHODS: This study employed a secondary data analysis using data derived from a previously conducted, 24+ week prenatal exercise intervention. At 16 weeks of gestation, women were randomized to one of four groups: aerobic training (n= 89), resistance training (n= 61), combined training (n= 66), and non-exercising comparison group (n= 83). Exercise training groups participated in 3, 50-minute, moderate-intensity exercise sessions per week. The non-exercising group participated in 3, 50-minute, low-intensity stretching and breathing sessions per week. Maternal glucose metabolism was measured using fasting serum glucose levels at 16, 25-27 and 36 weeks of gestation. GDM diagnoses were extracted from medical records and determined via oral glucose tolerance tests (OGTT) performed at prenatal clinics between 25-27 weeks of gestation. Three separate ANCOVA regression models were performed to evaluate the differential effects of prenatal exercise training type on maternal glucose metabolism at 25-27 weeks (using OGTT values), 36 weeks and the change from mid-to-late pregnancy (16-36 weeks). Maternal peak oxygen consumption and pre-pregnancy body mass index served as covariates. RESULTS: Prior to randomization into intervention groups baseline measures were taken from 299 women, including, age, pre-pregnancy body mass index (BMI), race and ethnicity, relative VO2 max, and estimated 1 repetition maximum. Following baseline measures 299 women were randomized into the following: AT n= 89, RT n= 61, CT n= 66, and CON n= 83. An ITT analysis comparing the non-exercising control group at 25-27 weeks gestation, exercise training AT: 113.1 ± 3.4 mg/dL, 95% CI (106.4, 119.7), RT: 116.4 ± 5.3 mg/dL, 95% CI (105.9, 126.9), CT:113.3 ± 4.7 mg/dL, 95% CI (104.0, 122.6), CON: 115.2 ± 4.0 mg/dL, 95% CI (107.2, 123.2). Similarly, no between group differences in exercise training type were observed, AT vs.