A 2012 study on 3027 women - published in Fertility and Sterility has confirmed the findings of previous studies that found intensive exercise - such as running, fast cycling, aerobics, gymnastics, and swimming - could harm female fertility delaying the time to pregnancy. Danish and US researchers found that as levels of vigorous exercise increased the time to conception in healthy, normal weight women increased. However, in overweight women - with a BMI over 25 - increased vigorous exercise did not have an adverse effect.

Moderate physical activity - such as brisk walking, leisurely cycling, golfing and gardening - did not adversely the time it took to conceive indicating that moderate - but not intense - activity is fertility- friendly. the study concluded that:

"There was evidence for a dose-response relationship between increasing vigorous PA (physical activity) and delayed TTP (time to pregnancy) in all subgroups of women with the exception of overweight and obese women."

"Moderate PA was associated with a small increase in fecundability regardless of BMI. These findings indicate that PA of any type might improve fertility among overweight and obese women, a subgroup at higher risk of infertility."

"Lean women who substitute vigorous PA with moderate PA may also improve their fertility."

This study was performed on women who were trying to conceive who were presumed fertile, ASRM  President-Elect, Linda Giudice, MD, PhD, noted that:

"This study is particularly interesting because its participants were recruited from the general population, not from infertility patients.  It points out the benefits of moderate exercise to all women who are planning a pregnancy and suggests that women might reduce their time to pregnancy by modulating their exercise programs."

It certainly *is* possible to conceive and carry a baby to term while running but it may be a minority of women who can do so given the unfavorable hormonal environment that is created by intense, frequent exercise.

While your physician may not have mentioned exercise as a factor in your infertility, if you are a runner or a spinner it may be wise to try switching some of your intense cardiovascular exercise for walking, yoga or another less aerobic activity that you enjoy. If you are taking clomiphene to induce ovulation make sure that your hormone levels are being carefully monitored and supported if your body is not yet producing adequate hormones after an extended period of running. Intense and frequent exercise is very healthy at most times of your adult life but you may need to hit the brakes a little while restoring a more fertility-friendly hormonal balance.


Ref. March 15 , 2012 by: ASRM Office of Public Affairs. Published in ASRM Press Release.  A prospective cohort study of physical activity and time to pregnancy Lauren A. Wise, Sc.D.,a,b Kenneth J. Rothman, Dr.P.H.,a,c Ellen M. Mikkelsen, Ph.D.,d Henrik Toft Sørensen, M.D.,a,d Anders H. Riis, M.S.,d and Elizabeth E. Hatch, Ph.D. Fertility and Sterility.