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

This work was partially supported by the program AL14-PID-39, AL15-PID-06, Technical University of Madrid, Spain.
https://doi.org/10.1016/j.ajog.2015.11.039Get rights and content

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.

Introduction

The prevalence of all pregnancies with some form of hypertension can be up to 10%,1 with the rates of diagnosis varying according to the country and population studied and the criteria used to establish the diagnosis.2 Although these clinical issues may range in severity from trivial to life threatening,1 elevated blood pressure (BP) remains the leading cause of maternal, fetal, and neonatal morbidity and mortality.2, 3 Gestational hypertension has been defined as elevated BP4 that develops >20 weeks of gestation in a previously normotensive woman, without proteinuria.1 These women are at high risk (15-45%) for developing preeclampsia1 with high BP,5 typically appearing >20 weeks of pregnancy in a normotensive woman, and most frequently including proteinuria.2 Preeclampsia may or may not progress to eclampsia with the occurrence of seizures and extreme maternal and fetal complications.5 Severity of symptoms can accelerate rapidly, leading to immediate delivery regardless of gestational age.5 Although the origin of pregnancy hypertension is unknown,6 many theories exist suggesting that the pathophysiological processes that lead to preeclampsia begin in early pregnancy, even though maternal symptoms do not appear until mid to late gestation.7

Although the causal link to pregnancy-induced hypertension is unknown, there are maternal factors, such as excessive gestational weight gain (GWG) regardless of prepregnancy body mass index (BMI), and maternal obesity8 that increase the risk for hypertensive disorders.9 In addition, there are downstream consequences of pregnancy-induced hypertension that have been linked to neonatal birthweight (macrosomia >4000 g; low birthweight <2500 g),10 leading to childhood obesity and cardiovascular disease risk in the offspring.10 It has been suggested that interventions focus on reducing modifiable risk factors (one of the most prominent being excessive GWG) should be incorporated into prenatal care to improve the health of the mother and reduce perinatal complications11 and cardiovascular risk.

Epidemiological evidence suggests that women who participate in regular physical activity have a reduced risk of developing pregnancy-induced hypertension12 and preeclampsia.13, 14, 15 These studies are based on retrospective questionnaires in case-control cohorts and, as recent reviews concluded, there is a critical need for well-designed randomized controlled trials (RCT).16, 17, 18 The aim of the present study was to examine the impact of a program of supervised exercise throughout pregnancy on the incidence of pregnancy-induced hypertension. We hypothesized that adherent women (≥80% attendance) to an exercise program initiated early in pregnancy (9-11 weeks’ gestation) will have a decreased incidence of pregnancy-induced hypertension and that exercise will protect against the initiation of this disease in women of all prepregnancy BMI categories, while also protecting against excessive GWG. In addition, we hypothesized that exercise protects against macrosomia (>4000 g) and low birthweight (<2500 g) and other pregnancy complications.

Section snippets

Materials and Methods

The present RCT (identifier: NCT01723098) was conducted from December 2011 through January 2015 following the ethical guidelines of the Declaration of Helsinki, last modified in 2000. The research protocol was reviewed and approved by the ethics review board of Hospital Severo Ochoa (Madrid, Spain). The onset of patient enrollment was November 2012.

Results

A total of 840 pregnant women met the criteria. After randomization, 38 women in the exercise group were lost to follow-up because of discontinued intervention (N = 17), ruptured membranes (N = 3), diagnosed incompetent cervix, obstetric risk of premature delivery (n = 6), and personal reasons (N = 12). In all, 37 participants in the control group were excluded from the study because of persistent bleeding (n = 6), diagnosed incompetent cervix, obstetric risk of premature delivery (n = 8), and

Comment

We examined the effects of physical training during pregnancy on the incidence of pregnancy-induced hypertension regardless of prepregnancy BMI. This novel approach used an integration of light resistance, toning, aerobic dance, and pelvic floor exercises in the training program, easily incorporated into a structured exercise regime. It appears that this program was equally liked by all BMI categories as indicated by the high adherence rate.

Interventions focusing on reducing modifiable risk

Acknowledgment

The authors would like to acknowledge the technical assistance of the Gynecology and Obstetrics Departments of Hospital Severo Ochoa, Hospital de Fuenlabrada, and Hospital Puerta de Hierro of Madrid.

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    The authors report no conflict of interest.

    Cite this article as: Barakat R, Pelaez M, Cordero Y, et al. Exercise during pregnancy protects against hypertension and macrosomia: randomized clinical trial. Am J Obstet Gynecol 2016;214:649.e1-8.

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