Obesity is associated with an increased risk of miscarriage, preterm delivery, stillbirth, low birthweight, and neonatal death. A recent systematic review and meta-analysis of 11 randomized controlled trials involving 5,931 participants showed that there were no differences in pregnancy rates between obese women treated with lifestyle interventions versus usual care. However, women who lost at least 7% of their body weight had higher odds of achieving pregnancy compared to women who did not lose weight. Women who lost less than 7% of their body mass experienced lower odds of pregnancy. There was also a trend toward improved obstetric outcomes among women who lost weight.
Women with obesity and unexplained infertility had similar success when treated with both dieting and exercise compared to just increasing physical activity. Both groups experienced a significant increase in their body mass index after treatment, however, the women who did both exercises and diets lost significantly more weight than those who just exercised. The women who did both exercises plus diets also saw a greater decrease in their waist circumference, blood pressure, and triglycerides. These improvements were sustained throughout the study period.
The senior investigators on the FIT-POSE trial, Drs. Richard Legro and David Jones, both OB/GYNs at Penn State Hershey Medical Center, told me, ‘We were surprised when we saw the results of the study. We had hypothesized that losing weight would lead to an increase in the chance of getting pregnant. However, we found that the women who lost weight actually had fewer pregnancies.’
“I think there’s a real opportunity here to start thinking about what kind of recommendations might be appropriate for fertility,” said Legro. He thinks that if we could figure out how to create healthy habits that last long term, we might be able to help women get pregnant naturally. “There’s a lot of research going into trying to understand whether it’s possible to change behavior. I think we should be doing that before we start recommending anything. We don’t know enough about the impact of different types of diets on fertility.”
“When researchers reviewed results from four randomized controlled trials, they found that exercise programs were just as effective as fertility treatments in boosting fertility. Women who exercised were twice as likely to get pregnant compared to those who did not exercise. However, there was no difference in pregnancy rates among women with polycystic ovary syndrome (PCOS) who participated in an exercise program versus those who didn’t.”