FROM OBSTETRICS AND GYNECOLOGY
Exercise and moderate weight loss – or even limited weight gain – during pregnancy can improve maternal outcomes, according to two recent studies.
Physical activity programs initiated during pregnancy can reduce the risk of gestational diabetes, according to results from a meta-analysis of randomized trials. And in another recently published study, researchers found that modest weight loss, or low weight gain, during pregnancy reduced the risk of gestational hypertension and certain adverse birth outcomes among obese women.
The meta-analysis , conducted by Brian W. Whitcomb, Ph.D., and colleagues at the University of Massachusetts, Amherst, and published in the March issue of Obstetrics & Gynecology, suggested a protective effect of exercise in pregnancy, though the included studies varied considerably in design and patient adherence (Obstet. Gynecol. 2015;125:576-82).
Of the 3,401 pregnant women in the 10 studies, the women randomized to aerobic exercise with or without strength training had a 28% lower risk of developing gestational diabetes mellitus than did women not randomized to exercise.
The studies varied in terms of types of interventions; some involved only walking, while others incorporated strength training and balance exercises. Body mass index was unrestricted in some, and other studies enrolled only overweight or obese women.
Adherence was as low as 16% in certain studies, and a third of patients were lost to follow-up, limiting the generalizability of the results. But the meta-analysis adds to the evidence base supporting an association between exercise during pregnancy and a lower risk of gestational diabetes mellitus, the researchers wrote.
“Because the benefit of exercise identified in this study occurred with physical activity that began after recognition of pregnancy and enrollment in prenatal care, these findings suggest clear future clinical and public health applications,” they wrote.
In a separate study also published in Obstetrics & Gynecology, a group of Belgian researchers found that obese women who lost weight during pregnancy or gained less weight than recommended under current Institute of Medicine guidelines had a reduced risk of gestational hypertension and emergency cesarean delivery, as well as macrosomia and large-for-gestational-age neonates (Obstet. Gynecol. 2015;125:566-75).
In contrast to some previous studies, no association was seen between weight loss or low weight gain and either low birth weight or smaller than gestational age.
This could be because earlier studies included women who were overweight, but not obese, which the researchers classified as a BMI of 30 or greater. “These two groups may have different metabolic rates, which could affect the neonatal outcomes,” they wrote.
Roland Devlieger, Ph.D., of University Hospitals Leuven, Belgium, and colleagues, analyzed records from more than 18,000 obese pregnant women who gave birth to singleton infants between 2009 and 2011. Among this group, 4.7% lost weight during their pregnancies (a mean weight loss of 5.96 kg) and 13.8% gained fewer than 5 kg, which is less than the recommended amount.
Women with gestational diabetes were excluded from the analysis, and investigators controlled for maternal and gestational age and parity, although they could not to control for maternal education, ethnicity, or smoking because of a lack of data.
In the adjusted multivariate analysis, weight loss and low gestational weight gain were associated with a decreased adjusted odds ratio of gestational hypertension for women with a BMI of 30-35. Weight loss was also associated with decreased macrosomia and large-for-gestational-age neonates across all classes of obesity (BMI 30-35, 35-40, and greater than 40) with the highest effect in women with a BMI of 40 or greater.
No association was seen between weight loss and low birth weight, small-for-gestational-age neonates, or admission to a neonatal intensive care unit across the different obesity classes.
“It appears that an increasing maternal BMI mitigates the effect of weight loss on fetal growth in terms of the probabilities of low birth weight and SGA neonates,” Dr. Devlieger and colleagues wrote in their analysis. “Our data show that obese women have better perinatal outcomes when they gain less than currently advised by the IOM, but this needs confirmation in prospective cohorts.”
While ideally, weight loss before conception should be emphasized by clinicians, “taking part in healthy lifestyle coaching programs during pregnancy with a focus on healthy diet and stimulating physical activity can have benefits for both the mother and child,” the researchers wrote.
None of the researchers reported having relevant financial disclosures. The Belgian study was funded by the Flemish Centre for Care and Health.
