03/21/2012 01:04 pm ET Updated Feb 20, 2015

Moderate Exercise Boosts Fertility, Study Says

If you’re trying to get pregnant, you could help speed up conception by taking a brisk walk or lazy bike ride -- but chances are a major sporting event like a triathlon will hinder it. That’s the finding from a new study of Danish women that suggests, when it comes to fertility, healthy-weighted women should choose moderate over intense exercise.

Conversely, for obese or overweight women, the association was a bit different: excess weight can interfere with fertility, but intensive exercise didn’t further hinder the ability to conceive among obese and overweight study participants.

Researchers looked at 3,000 women who were trying to get pregnant and were not undergoing fertility treatment. They asked the women to fill out questionnaires about their activity level and then tracked to see how long it took them to conceive. Researchers found that women who engaged in five or more hours a week of rigorous exercise -- things like running, aerobics, spinning and other intense workouts -- were nearly half as likely to get pregnant in a single month as those who engaged in only moderate exercise (defined as walking, gardening, and other leisure activities). And women of all weights conceived more quickly when they were moderately active instead of sedentary.

The takeaway? If you’re overweight, you’re at a disadvantage, but exercise at any level will help. If you’re a healthy weight, stick to moderate activity, but don’t slow down too much: a sedentary lifestyle won’t help anyone.