Women who have experienced pregnancy loss may increase their chances of falling pregnant by walking, according to new research, which found that small bouts of walking were associated with a higher likelihood of conceiving among women who were overweight or obese.
As part of a study published in the journal Human Reproduction, researchers explored the relationship between physical activity and fecundability, or the ability to fall pregnant. A team from the University of Massachusetts Amherst recruited 1200 women aged 18 - 40 with a history of one - two pregnancy losses.
Women were questioned about how often and for how long they walked, as well as how frequently they engaged in "moderate intensity" activity and "vigorous intensity" activity for at least 10 minutes at a time, over the previous seven days. Participants were followed for up to six menstrual cycles as they tried to conceive, then throughout pregnancy for women who fell pregnant.
And the results were positive - at least when it comes to walking.
"One of our main findings is that there was no overall relationship between most types of physical activity and the likelihood of becoming pregnant for women who had already had one or two pregnancy losses, except for walking, which was associated with higher likelihood of becoming pregnant among women who were overweight or obese," said co-author Lindsey Russo.
More specifically, women with a BMI greater than 25, those who reported "some walking" had a higher conception probability than those who reported no walking at all (at least not for longer than ten minutes at time).
Interestingly, women who engaged in physical activity of "vigorous intensity" for greater than four hours a week were also more likely to fall pregnant, regardless of their BMI.
"What we eat and what we do are potential factors we can change to shape our health. So this sort of research is important because it helps provide information on the things people can actually do something about," said co-author Brian Whitcomb. "We were happy to be able to add scientific evidence to general recommendations about physical activity. This is especially true for the results about walking for even limited blocks of time."
Walking, Mr Whitcomb said, has "great potential" as a lifestyle change, because of its low cost and availability.
The authors note that exactly how walking and vigorous activity might affect time-to-pregnancy requires more study."We don't know what to make of the finding that high intensity physical activity may have different biological effects than walking, but our study doesn't offer enough detail to get at why vigorous activity would work differently than other levels,' Mr Whitcomb said.
There are some caveats, however. Given the study only focused on women with a history of pregnancy loss, the findings may not be relevant for other women who are trying to conceive. "In addition," the authors note, "exercise habits may differ in women with prior miscarriage compared to those without."
Previous research published in Fertility and Sterility, found that moderate exercise (such as walking, cycling, or gardening) was associated with a shorter time-to-pregnancy, while those who exercised vigorously took longer to conceive (with the exception of women who were overweight or obese). "Lean women who substitute vigorous physical activity with moderate physical activity may also improve their fertility," the authors wrote.