Exercise During Pregnancy Protects Against Hypertension and Macrosomia: Randomized Clinical Trial

Full text

Exercise During Pregnancy Protects
Against Hypertension and Macrosomia:
Randomized Clinical Trial
Ruben Barakat, Mireia Pelaez, Yaiza Cordero, Maria Perales, Carmina Lopez,
Javier Coteron, and Michelle F. Mottola
Physical Activity and Sports in Specific Populations (AFIPE) Research Group, Faculty of Physical Activity and Sports
Sciences-Facultad de Ciencias de la Actividad Física y el Deporte, Technical University of Madrid, Madrid (R.B., M. Pelaez,
M. Perales, C.L., J.C.); Catholic University of Murcia, Murcia (Y.C.), Spain; and R. Samuel McLaughlin Foundation-Exercise and
Pregnancy Laboratory, School of Kinesiology, Faculty of Health Sciences, Department of Anatomy and Cell Biology, Schulich School
of Medicine and Dentistry, Children's Health Research Institute, University of Western Ontario, London, Ontario, Canada (M.F.M.)
Am J Obstet Gynecol 2016;214:649.e1–649.e8
ABSTRACT
Up to 10% of all pregnancies are affected by some form of hypertension, with the rates of diagnosis varying according to the
country, population studied, and the criteria used to diagnose the problem. Since these clinical issues may range in severity,
elevated blood pressure remains a leading cause of maternal, fetal, and neonatal morbidity and mortality. Conditions such as
prepregnancy obesity and excessive gestational weight gain (GWG) of all body mass index (BMI) categories have been as-
sociated with maternal hypertensive disorders. In addition, these factors are also linked to both macrosomia (>4000 g) and low
birth weight (<2500 g). To date, there has not been a large randomized controlled trial with high adherence to an exercise pro-
gram that has been performed to examine pregnancy-induced hypertension and these associated issues. Thus, the objective of
this study was to investigate whether women compliant (≥80% attendance) to an exercise program initiated early in pregnancy
showed a reduction in pregnancy-induced hypertension and excessive GWG in all prepregnancy BMI categories. In addition,
it aimed to determine whether maternal exercise protected against macrosomia and low birth weight.
A randomized controlled trial was conducted from 2011 to 2015. Participants included women with singleton and uncom-
plicated pregnancies (without type 1, type 2, or gestational diabetes mellitus at baseline) without a history of preterm delivery.
These women were randomized into an exercise group (n = 382) or a control group (n = 383) receiving standard care. Partic-
ipants in the exercise group were trained 3 days/wk (50–55 minutes per session) from first trimester until 38 to 39 weeks. Each
of the approximately 85 training sessions involved aerobic exercise, muscular strength, and flexibility. Results of the study
showed that pregnant women who did not exercise were 3 times more likely to develop hypertension (odds ratio [OR],
2.96; 95% confidence interval [CI], 1.29–6.81; P= 0.01) and were 1.5 times more likely to gain excessive weight (OR,
1.47; 95% CI, 1.06–2.03; P= 0.02) compared with those with high attendance to the exercise program. The study also found
that pregnant women who do not exercise were also 2.5 times more likely to give birth to a macrosomic infant (OR, 2.53; 95%
CI, 1.03–6.20; P= 0.04). The study concluded that exercise during pregnancy may be a useful preventative tool for hyperten-
sion and excessive GWG. It may also help to reduce macrosomia while reducing comorbidities related to chronic disease risk.
EDITORIAL COMMENT
(Preeclampsia is responsible worldwide for a
large proportion of maternal and neonatal morbid-
ity and mortality (Lancet. 2010;376:631–644). In
the United States, whereas maternal mortality from
preeclampsia decreased in the 20th century, pre-
eclampsia still causes 18% of the maternal deaths
each year (Obstet Gynecol. 1996;88:161–165)
Additionally, it is a leading cause of indicated
preterm delivery that leads to the negative im-
pact on neonatal morbidity and mortality (Am J
Obstet Gynecol. 1998;178:562–567). As a field,
we have been trying to reduce the risk of pre-
eclampsia for decades. Randomized trials of aspi-
rin, antioxidants, and calcium have demonstrated
www.obgynsurvey.com | 505
Volume 71, Numbe r 9
OBSTETRICAL AND GYNECOLOGICAL SURVEY
Copyright ©2016 Wolters Kluwer Health, Inc. All rights reserved.
OBSTETRICS
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

modest benefit at best, but most trials have been
negative (Cochrane Database Syst Rev. 2015;29:
CD004072; Cochrane Database Syst Rev. 2014;
24:CD001059). Even when positive, for example,
with aspirin, there is only a 10% to 20% reduc-
tion in preeclampsia.
Perhaps our approaches have been too medical.
A medical approach often attempts to treat disease
when it happens or with pharmaceutical prevention
as opposed to seeking prevention through attain-
ment of greater levels of health. One of the key tran-
sitions in most of the labor force in the developed
world has been the shift from jobs that require
physical activity to jobs that require sitting in front
of a computer screen. Thus, the amount of daily
physical activity of the average adult has decreased
dramatically over the past hundred years. With this
transition have come the obesity epidemic and the
need for recommended levels of exercise.
Exercise in pregnancy has been historically
understudied, partly owing to lingering concerns
that aerobic exercise may steal cardiac output
from the uterus and placenta and potentially
cause fetal growth restriction. In a prior lifestyle in-
tervention that included recommended exercise
levels, the impact was modest, no impact on aver-
age gestational weight gain, although the propor-
tion with excessive GWG was reduced (BJOG.
2011;119:70–77). A similar finding of a reduction
in the proportion of women who gained excessive
weight gain from 52% to 41% was demonstrated
in a previous trial of counseling on exercise (Am J
Clin Nutr. 2011;93:772–779). Neither of these
studies found a difference in any other clinical out-
comes, although they may have been underpow-
ered to do so.
In the study abstracted above, the authors
randomized pregnant women to three 50- to
55-minute exercise sessions per week versus
standard care. On average, those randomized
to exercise had 80 to 85 exercise sessions dur-
ing pregnancy. Remarkably, the authors found
that the rate of gestational hypertension and
preeclampsia both decreased by two thirds.
Additionally, they found reductions in excessive
GWG, gestational diabetes, and macrosomia.
Interestingly, when the analyses were stratified
by BMI threshold, they were generally consis-
tent for normal-weight and overweight women,
but less so for obese women.
These findings are remarkable. An intervention
with a greater than 50% reduction in preeclamp-
sia has enormous potential and may ultimately
reduce neonatal morbidity and mortality from iat-
rogenic preterm birth. With regard to generaliz-
ability, one problem in the US is that the kind of
adherence to the exercise program of 80% or
greater is generally not achieved from exercise
recommendations but only with paid gym mem-
berships or specific assigned personal trainers.
Currently, insurance plans do not pay for such
expensive interventions, although it has been
discussed from a policy perspective. Thus,
whereas providers can recommend exercise and
use the findings from this trial to support such rec-
ommendations, the chance that the exercise
levels seen in this study would be achieved with-
out other structural changes is unlikely. Thus, it
is incumbent upon clinical providers, health sys-
tems, public health workers, health policy experts,
and other advocates to work to make exercise
easier. Certainly, this is true for pregnant women,
but also true for all people; the benefits of exercise
are far-reaching, and we should all work to make
increased physical activity part of our patients'
lives and our own.—ABC)
506 Obstetrical and Gynecological Survey
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.