How Much Activity Enhances Fertility? A New Study Says...

Balance is one of the hardest things to achieve in life, and it seems like that's especially true for women who are trying to get pregnant. You know that overall health and fitness play a role in fertility, but you've also heard that there really can be too much of a good thing. Trying to keep up with the "do this, do that" of research data can make you want to throw your hands up and say "I quit!"

Image: Ambro / FreeDigitalPhotos.net 

But you don't have to be an exercise physiologist or a registered dietitian to understand a few simple points amid the building database of knowledge about fertility's connections to weight and physical activity.

And here's the latest: Moderate activity wins the game. Again.

A just-released study (from Fertility & Sterility) of more than 3,000 Danish and U.S. women ages 18 to 40 found that moderate levels of physical activity resulted in "small decreases in time to pregnancy" for women of all body mass index (BMI) levels.

If you're struggling to get pregnant, that finding may not seem so exciting. But factor in the rest of the story and fertility patients may feel a little uplifted by this study.

Importantly, the subjects in this study were drawn from the general population, not from among fertility patients. Requirements of participation included:

• being in a stable relationship with a male partner
• planning to get pregnant
• not receiving fertility treatment

Participants were followed for a year or until they conceived. The researchers looked at several variables, including differences in length of time to conception for women throughout the BMI range. They found that vigorous physical activity either works against you (for women of "normal weight," BMI under 25) or doesn't do anything for you (for overweight or obese women, BMI of 25 or above) in terms of time it took to get pregnant.

In this study, vigorous activity included running, fast cycling, aerobics, gymnastics, and swimming.

The "winners" -- in this case, those who took the shortest amount of time to pregnancy -- were women who engaged in 20 to 39 MET hours (total metabolic equivalents assigned to different kinds of activity) per week of physical activity. And moderate activity was key.

Though the authors concede more data is warranted to investigate different types of physical activity in relation to fertility, their study suggests that overweight or obese women might benefit from any physical activity and lean women will likely enhance their fertility by switching to moderate, rather than vigorous, activity.

So what's moderate?

Brisk walking, leisurely cycling, golfing and gardening.


Source: A prospective cohort study of physical activity and time to pregnancy
             L. A. Wise et al., Fertil Steril 2012

If You're Trying to Conceive, Skip the Triathlon. Try Yoga.

Along the same lines as there being no magic to getting pregnant, whether with IVF or without treatment, there's also no perfect exercise that will lead to conception.


But... yoga comes close.


Conception (and pregnancy) have much to do with balance. Not too much of this, and just the right amount of that. Your fitness factors, including your weight and body mass index, flexibility and strength, all play roles in keeping your endocrine system humming along.


Choice of exercise is a very personal thing. You should take several things into consideration when choosing the type, level, and frequency of physical exertion you engage in, whether you're trying to conceive or not. For example, running isn't the safest idea for everyone, but for some, it's perfect. Swimming is great, but not everyone has regular, easy access to a pool. The same could be said of biking.


As this article in The Windsor Star describes, yoga is about more than stretching and posing. If done well, yoga can both strengthen and relax your body, which is a state of being that facilitates hormone health.


You may want to avoid the most rigorous forms of yoga (there are many different versions), including the forms that are taught in studios heated above 90 degrees. And if you can find a yoga instructor who knows specific poses that are good for your reproductive organs, that's a bonus. (Here at Houston Fertility Center, we'll help you find one...)


Remember, you're looking for balance through activity.
Put your dreams of being a triathlete on hold until after the baby comes, but don't shelve your body's need to move and breathe.


~Dr. Sonja Kristiansen MD