Exercise level, preconception BMI affect conception

Moderate exercise is associated with shorter time to conception for women regardless of their weight; however, there is an inverse association between intensity of exercise and time to conception in normal-weight women.

Women who want to become pregnant should be counseled about their exercise regimen.

The benefits of regular physical exercise include improved cardiovascular health, reduced risk of diabetes, and improved pregnancy outcomes, but a Danish prospective cohort study suggests that a woman’s workout intensity may affect how long it takes for her to conceive.

The study of 3,628 women aged 18 to 24 found that moderate physical activity-about 5 hours per week of brisk walking, golfing, cycling-appears to shorten time to conception in women regardless of weight.

However, as physical activity intensified (that is, >5 hours per week of running, fast cycling, aerobics, swimming), time to conception was delayed in healthy normal-weight women (BMI ≤25 kg/m²) although overweight and obese women (BMI >25 kg/m²) were unaffected.

None of the women were being treated for infertility; all were healthy, in stable relationships with male partners, and planning to become pregnant.

The authors noted that exercise of any intensity appeared to facilitate conception in overweight and obese women, who normally have greater difficulty in conceiving, and those who engage in vigorous rather than moderate physical activity also may see a fertility benefit. Leaner women contemplating conception should be advised to modulate the intensity of their workouts.

Results were published in Fertility and Sterility. 2012; in press.

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