Diet and exercise during pregnancy was associated with a lowered chance of caesarean section delivery, researchers reported.
In a meta-analysis of individual participant data from 32 studies involving more than 11,000 women, the odds of a C-section delivery were significantly reduced with weight control interventions during pregnancy (OR 0.91, 95% CI 0.83-0.99, I2=0%).
Pooled data on more than 9,000 women in 33 studies yielded a weight-gain benefit from diet and physical-activity based intervention, compared to an absence of intervention (mean difference -0.70 kg or -1.54 lb, 95% CI -0.92 to -0.48 kg, I2=14.1%).
Led by The International Weight Management in Pregnancy (i-WIP) Collaborative Group of over 50 researchers, the findings were published in The BMJ.
“Half of all women of childbearing age worldwide are overweight or obese,” the research group highlighted. While the benefits of diet and physical activity during pregnancy are well recognized, the specific subgroups who may benefit most from such intervention, as well as the implications on maternal and child outcomes, have not been fully identified.
In order to address these concerns, the researchers performed a literature review through several major databases to identify randomized trials regarding diet and exercise-related intervention initiated during pregnancy. Dietary interventions used in the included trials utilized intervention such as an increase in vegetables and fruits and limiting sugar-sweetened beverage intake. Physical activity based interventions included resistance training, stationary cycling, and aerobic-based group classes.
Using individual participant data from 36 randomized trials from 16 countries, a two-stage meta analysis was conducted. The first stage involved a separate cluster analysis of each individual trial, while the second stage pooled all trial data together to assess sub-group differences (n=12,526).
No significant subgroup effects were reported for age, baseline BMI, parity, or underlying medical conditions, suggesting that all groups may benefit from lifestyle interventions.
In addition to C-section risk reduction, a decreased risk for gestational diabetes was associated with interventions that were mostly exercise-based (OR 0.67, 95% CI 0.46-0.99, I2=0%; 10 studies, 2,700 women). However, intervention was not found to be significantly linked to composite maternal (OR 0.90, 95% CI 0.79-1.03, I2=26.7%) or offspring outcomes (OR 0.94, 0.83-1.08, I2=0%).
Rates of adverse events were also not significantly higher among women who participated in diet and physical activity interventions.
“Our findings are important because it is often thought that pregnant women shouldn’t exercise because it may harm the baby,” said co-author Shakila Thangaratinam, PhD, from Queen Mary University of London’s Barts Research Centre for Women’s Health, in a press release. “But we show that the babies are not affected by physical activity or dieting, and that there are additional benefits including a reduction in maternal weight gain, diabetes in pregnancy, and the risk of requiring a caesarean section.
“This should be part of routine advice in pregnancy, given by practitioners as well as midwives. Now that we’re able to link the advice to why it’s beneficial for mothers-to-be, we hope mothers are more likely to adopt these lifestyle changes.”
In an accompanying editorial, Marian Knight, DPhil, of the University of Oxford, and Charlie Foster, PhD, of the University of Bristol in England, praised the study for identifying an intervention to significantly reduce the rate of C-section, given the notably high rates in the analysis (34.8% intervention; 37.7% control). However, Knight and Foster were skeptical of how consequential a weight loss of less than 1 kg could be.
Additionally, they cited the wide range of different physical activity interventions included in the analysis as a limitation. Instead, Knight and Foster recommended future studies should focus on specific types and patterns of exercise that may yield better outcomes for various populations.
“For example, future studies could explore a possible role for strength and balance training in improving pregnancy outcomes, and consider whether pregnancy could be a window of opportunity to change physical activity patterns among women and their families in the longer term,” they wrote.