A randomized clinical trial of exercise during pregnancy to prevent gestational diabetes mellitus and improve pregnancy outcome in overweight and obese pregnant women.
BACKGROUND
Obesity and being overweight are becoming epidemic, and indeed, the proportion of such women of reproductive age has increased in recent times. Being overweight or obese prior to pregnancy is a risk factor for gestational diabetes mellitus, and increases the risk of adverse pregnancy outcome for both mothers and their offspring. Furthermore, the combination of gestational diabetes mellitus with obesity/overweight status may increase the risk of adverse pregnancy outcome attributable to either factor alone. Regular exercise has the potential to reduce the risk of developing gestational diabetes mellitus and can be used during pregnancy; however, its efficacy remain controversial. At present, most exercise training interventions are implemented on Caucasian women and in the second trimester, and there is a paucity of studies focusing on overweight/obese pregnant women.


OBJECTIVE
We sought to test the efficacy of regular exercise in early pregnancy to prevent gestational diabetes mellitus in Chinese overweight/obese pregnant women.


METHODS
This was a prospective randomized clinical trial in which nonsmoking women age >18 years with a singleton pregnancy who met the criteria for overweight/obese status (body mass index 24≤28 kg/m2) and had an uncomplicated pregnancy at <12+6weeks of gestation were randomly allocated to either exercise or a control group. Patients did not have contraindications to physical activity. Patients allocated to the exercise group were assigned to exercise 3 times per week (at least 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 control group continued their usual daily activities. Both groups received standard prenatal care, albeit without special dietary recommendations. The primary outcome was incidence of gestational diabetes mellitus.


RESULTS
From December 2014 through July 2016, 300 singleton women at 10 weeks' gestational age and with a mean prepregnancy body mass index of 26.78 ± 2.75 kg/m2were recruited. They were randomized into an exercise group (n = 150) or a control group (n = 150). In all, 39 (26.0%) and 38 (25.3%) participants were obese in each group, respectively. Women randomized to the exercise group had a significantly lower incidence of gestational diabetes mellitus (22.0% vs 40.6%; P < .001). These women also had significantly less gestational weight gain by 25 gestational weeks (4.08 ± 3.02 vs 5.92 ± 2.58 kg; P < .001) and at the end of pregnancy (8.38 ± 3.65 vs 10.47 ± 3.33 kg; P < .001), and reduced insulin resistance levels (2.92 ± 1.27 vs 3.38 ± 2.00; P = .033) at 25 gestational weeks. Other secondary outcomes, including gestational weight gain between 25-36 gestational weeks (4.55 ± 2.06 vs 4.59 ± 2.31 kg; P = .9), insulin resistance levels at 36 gestational weeks (3.56 ± 1.89 vs 4.07 ± 2.33; P = .1), hypertensive disorders of pregnancy (17.0% vs 19.3%; odds ratio, 0.854; 95% confidence interval, 0.434-2.683; P = .6), cesarean delivery (except for scar uterus) (29.5% vs 32.5%; odds ratio, 0.869; 95% confidence interval, 0.494-1.529; P = .6), mean gestational age at birth (39.02 ± 1.29 vs 38.89 ± 1.37 weeks' gestation; P = .5); preterm birth (2.7% vs 4.4%, odds ratio, 0.600; 95% confidence interval, 0.140-2.573; P = .5), macrosomia (defined as birthweight >4000 g) (6.3% vs 9.6%; odds ratio, 0.624; 95% confidence interval, 0.233-1.673; P = .3), and large-for-gestational-age infants (14.3% vs 22.8%; odds ratio, 0.564; 95% confidence interval, 0.284-1.121; P = .1) were also lower in the exercise group compared to the control group, but without significant difference. However, infants born to women following the exercise intervention had a significantly lower birthweight compared with those born to women allocated to the control group (3345.27 ± 397.07 vs 3457.46 ± 446.00 g; P = .049).


CONCLUSIONS
Cycling exercise initiated early in pregnancy and performed at least 30 minutes, 3 times per week, is associated with a significant reduction in the frequency of gestational diabetes mellitus in overweight/obese pregnant women. And this effect is very relevant to that exercise at the beginning of pregnancy decreases the gestational weight gain before the mid-second trimester. Furthermore, there was no evidence that the exercise prescribed in this study increased the risk of preterm birth or reduced the mean gestational age at birth.
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Chen
C
Wang
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Yumei
Y
Wei
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Xiaoming
X
Zhang
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Yue
Y
Zhang
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Qianqian
Q
Xu
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Yiying
Y
Sun
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Shiping
S
Su
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Li
L
Zhang
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Chunhong
C
Liu
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China.
Yaru
Y
Feng
Division of Hospital Medicine, Hallmark Health System, Medford, MA.
Chong
C
Shou
Schools of Sport Science, Exercise, and Health, University of Western Australia, Perth, Australia.
Kym J
KJ
Guelfi
Women's and Infants' Health, University of Western Australia, Perth, Australia.
John P
JP
Newnham
Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China. Electronic address: yanghuixia@bjmu.edu.cn.
Huixia
H
Yang
D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data; D002681:China / Q000453:epidemiology; D016640:Diabetes, Gestational / Q000517:prevention & control*; D015444:Exercise; D005260:Female; D005320:Fetal Macrosomia / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology; D007231:Infant, Newborn; D007333:Insulin Resistance; D009765:Obesity / Q000628:therapy*; D050177:Overweight / Q000628:therapy*; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology; D011446:Prospective Studies; D015430:Weight Gain
adverse pregnancy outcome; exercise; gestational diabetes mellitus; obesity; overweight; pregnant women