Exercise during pregnancy protects against hypertension and macrosomia: randomized clinical trial

Background: The prevalence of all pregnancies with some form of hypertension can be up to 10%, with the rates of diagnosis varying according to the country and population studied and the criteria used to establish the diagnosis. Prepregnancy obesity and excessive gestational weight gain (GWG) of all body mass index (BMI) categories have been associated with maternal hypertensive disorders and linked to macrosomia (>4000 g) and low birthweight (<2500 g). No large randomized controlled trial with high adherence to an exercise program has examined pregnancy-induced hypertension and these associated issues. We investigated whether women adherent (≥80% attendance) to an exercise program initiated early showed a reduction in pregnancy-induced hypertension and excessive GWG in all prepregnancy BMI categories, and determined if maternal exercise protected against macrosomia and low birthweight.

Objective: We sought to examine the impact of a program of supervised exercise throughout pregnancy on the incidence of pregnancy-induced hypertension.

Study design: A randomized controlled trial was used. Women were randomized into an exercise group (N = 382) or a control group (N = 383) receiving standard care. The exercise group trained 3 d/wk (50-55 min/session) from gestational weeks 9-11 until weeks 38-39. The 85 training sessions involved aerobic exercise, muscular strength, and flexibility.

Results: High attendance to the exercise program regardless of BMI showed that pregnant women who did not exercise are 3 times more likely to develop hypertension (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.29-6.81, P = .01) and are 1.5 times more likely to gain excessive weight if they do not exercise (OR, 1.47; 95% CI, 1.06-2.03, P = .02). Pregnant women who do not exercise are also 2.5 times more likely to give birth to a macrosomic infant (OR, 2.53; 95% CI, 1.03-6.20, P = .04).

Conclusion: Maternal exercise may be a preventative tool for hypertension and excessive GWG, and may control offspring size at birth while reducing comorbidities related to chronic disease risk.