Physical exercises and pregnancy

22.07.2013

But I’m in great shape! she said in frustration after I told her that her exercise routine could be hurting her chances of getting pregnant. It is a common but difficult conversation to have. Now, because of a new study, this conversation will become even more common.

We have known for a long time that extremes of weight and exercise can affect a woman’s chances of becoming pregnant.

The classic example is the very thin ballerina whose periods have stopped and who cannot get pregnant. Marathon runners and tri-athletes can have similar problems. Well this new study will now make us pay more attention to what we once thought were healthy levels of exercise.

The study looked at 3,628 women from Denmark who answered questions about their exercise habits and who were then followed for 12 months. Researchers compared women who engaged in vigorous exercise (described as running, fast cycling, aerobics, gymnastics, swimming etc.) to women who engaged in moderate exercise (described as brisk walking, leisurely cycling, golfing, gardening etc.). Exercise was also broken down by the numbers of hours per week.

The researchers found that women who engaged in as little as two or more hours of vigorous exercise a week had a lower monthly pregnancy rate than women who did not exercise at all (None = 17.5% and >=5 hours = 14.2%). However, women who engaged in moderate exercise showed a trend towards a better monthly pregnancy rate than those who did not partake (>= 5 hr per week = 16.8% compared to only 1 hr per week = 14%).

When they broke it down by weight, they found that woman who had a normal weight (body mass index (BMI) < 25) had the most negative effect of vigorous exercise on pregnancy rates (None = 19.8% and >=5 hrs = 13.5%). Overweight women (BMI >=25) did not show a negative effect of vigorous exercise.

The moral to this story seems to be like most things in life “ the story of Goldilocks and the three bears. When it comes to exercise and fertility you don’t want too much or too little of a good thing. It needs to be just right.

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