A new Danish study looked at 3,600 women who were trying to get pregnant, grouped them by BMI, and monitored their exercise habits. The researchers found that in normal weight women, too much strenuous exercise could cause delays in conception. So, what does that mean for you?
The study came out in the journal Fertility and Sterility, and it found that depending on your current BMI, exercise can impact your fertility in different ways. Moderate exercise, like walking or gardening, can actually boost your fertility, regardless of your BMI. In normal-weight women, however, more vigorous exercise may make it harder to conceive.
What the study is referring to when it talks about strenuous or vigorous exercise is intense workouts like running (especially distance running), intense cycling, and aerobics.
The other interesting finding from this study is that vigorous exercise actually seemed to help fertility in overweight and obese women (women with a BMI of 25 or higher).
Researchers did take other factors that can affect fertility into account, like smoking and alcohol use, but as always correlation does not equal causation. There’s definitely a link between vigorous exercise among normal weight women and a delay in conception, but that doesn’t necessarily mean that one is causing another. As Lauren Wise, one of the study’s authors, told The Boston Globe:
The take home message is that moderate physical activity appears to enhance fertility among all groups of women. Women at a healthy weight who exercise vigorously may want to switch to lighter activity if they’re having trouble getting pregnant.
Don’t despair, my marathon-running friends! If you’re trying to get pregnant and having trouble, you don’t necessarily have to ditch those running shoes. The negative results seemed to affect women who engaged in vigorous exercise for five or more hours per week, so cutting back your mileage just might do the trick. Of course, you’ll want to talk to your OB/GYN or a fertility specialist if you continue having trouble, but don’t let this study kick your running habit to the curb if you’re not having problems conceiving.