Exercise during pregnancy to prevent gestational diabetes mellitus and improve outcomes in overweight /obese pregnant women: A randomized controlled trial

摘要

Background: The portion of overweight/obese women of reproductive age has increased recently. Being overweight/ obese is a risk factor for gestational diabetes mellitus (GDM), and increases the risk of adverse outcome for both mothers and their offspring. Regular exercise has the potential to reduce the risk of developing GDM, however, its efficacy remain controversial. At present, most exercise interventions are implemented on Caucasian women and in the second trimester, and there is a paucity of studies focusing on overweight/obese pregnant women. Thus we aimed to test the efficacy of regular exercise in early pregnancy to prevent GDM in Chinese overweight/obese pregnant women. Methods: This was a prospective randomized clinical trial in which non-smoking women over 18 with a singleton pregnancy and met the criteria for overweight/obese status (BMI < 28 kg/m~2; obese, BMI ≥ 28kg/m~2) and an uncomplicated pregnancy at less than 12 weeks of gestation were randomly allocated to either exercise group (EG) or a control group (CG). Patients allocated to the EG were assigned to exercise 3 times per week (no less than 30 min/session with a rating of perceived exertion between 12-14) via a cycling program begun within 3 days of randomization until 37 weeks of gestation. Those in the CG continued their usual daily activities. Both groups received standard prenatal care. The primary outcome was incidence of GDM. Results: From December 2014 to July 2016, 300 singleton women at 10 gestational age and with a mean pre-pregnancy BMI of 26.78 ± 2.75 kg/m were recruited. They were randomized into an EG (n= 150) or a CG (150). (1) Women randomized to the EG had significantly lower incidence of GDM (22.0% vs. 40.6%, p<0.001).These women also had significantly (2) less gestational weight gain (4.08 ± 3.02 kg vs. 5.92 ± 2.58 kg, p < 0.001) by 25 gestational weeks and at the end of pregnancy (8.38 ±3.65 kg vs. 10.47 ±3.33 kg, p< 0.001), and (3) reduced insulin resistance levels (2.92 ± 1.27 vs. 3.38 ±2.00, p = 0.033) at 25 gestational weeks. Other secondary outcomes, including (4) hypertensive disorders of pregnancy (17.0% vs. 19.3%; OR, 0.854; 95% CI, 0.434-2.683, P = 0.6), (5) cesarean delivery (except for scar uterus) (29.5% vs. 32.5%;OR, 0.869; 95% CI, 0.494 -1.529, P = 0.6), (6) mean gestational age at birth (39.02 ±1.29 vs. 38.89 ±37 weeks gestation; P = 0.5); (7) preterm birth (2.7% vs. 4.4%, OR, 0.600; 95% CI, 0.140-2.573, P = 0.5), (8) macrosomia (defined as birth weight above 4000 g) (6.3% vs. 9.6%; OR, 0.624; 95% CI, 0.233-1.673, P = 0.3) and (9) large for gestational age infants (14.3% vs. 22.8%; OR, 0.564; 95% CI, 0.284-1.121, P = 0.1) were also lower in the EG compared to the CG, but without significant difference. However, infants born to women following the exercise intervention had a significantly lower birth weight compared with those born to women allocated to the CG (3345.27± 397.07 g vs. 3457.46 ± 446.00 g, P = 0.049). Conclusions: Cycling exercise initiated early in pregnancy is associated with a significant reduction in the frequency of GDM in overweight/obese pregnant women. Furthermore, it did not increase the risk of preterm birth or reduce the mean gestational age at birth.