Will exercise cause or prevent a miscarriage?

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I sat with the nicest new patient last night- 40-ish year old woman, former professional athlete who lived a pretty high stress lifestyle and who was looking for support after a miscarriage and 2 failed IVF rounds.  One thing really stood out to me- now that she had had a miscarriage, she was petrified to exercise. 

I come across this common myth often- that exercise can derail fertility, that it will screw with hormone levels, or that it could shake loose a pregnancy. 

This misconception stinks, for lack of a better word, because exercise is so GOOD for women trying to conceive and for women who are pregnant.  Exercise can help prevent aches and pains, can promote hormone balance, can be a HUGE stress manager, and more. 

In a 2014 study of 1000 women in the UK, 46.9% of women reported reducing their exercise when they became pregnant, and 12% stopped completely.  Almost a third of women reported that this was because they were concerned that it would increase their risk of miscarriage.  Despite no evidence of exercise contributing to miscarriage risk, this is still a HUGE worry for women.

Last month, this topic was discussed in Human Reproduction- a study of about 1,200 healthy women aged 18-40 and with 1-2 prior pregnancy losses were followed while attempting pregnancy and after they became pregnant.  For obese and overweight women, walking 10 minutes or more at a time was related to improved fecundability (the likelihood of a woman to get pregnant by with each cycle), with walking nearly doubling the odds ratio of pregnancy.  Women who exercised vigorously for 4 hours or more per week also increased their odds of pregnancy compared to women who didn’t exercise (no matter their BMI).  This study (remember, looking at women who had experienced a prior miscarriage) provides evidence that physical activity, including vigorous activity, can lower your time to pregnancy and doesn’t have a negative impact on that pregnancy- it doesn’t cause miscarriage.

So, what exercise is right for you?

Generally, I recommend that if you are overweight or obese, exercise should be a key part of your treatment plan.  Exercise helps to balance your blood sugar, rev your metabolism, helps you lose weight and reset hormone levels.  (For example, fat tissue is one place women make estrogen- estrogen dominance is FAR more common in women who are overweight!)

Aim to exercise 4-5 times per week for a minimum of 30 minutes.  I recommend moving weight (either free weights or your own body) in a way that gets your heart rate up.  I like functional exercises- things you’ll do every day- that work multiple parts of the body at once (think squats, lunges, planks, etc). 

For women at a healthy body weight or you fitness fanatics, feel free to do the above, or workout at the level you are today- no need to slow down if you’re doing more. 

How much is too much?

Exercise can have a negative impact on fertility when overdone (like all things… ).  Be sure you are taking at least 1 day off per week, and if you’re a heavy exerciser (like 6 days a week of cross fit), think about toning it back to 5 days and having the other days be focused on more restorative exercise, like walking, yoga, or nookie.

Not sure where to get started?  Download the free app (or search on youtube) for the 7 minute workout.  This awesome workout can be done several times to make even a 30 minute workout.  It goes by quick and provides exercises that can be done anywhere with minimal equipment.

References

Russo et al. Hum Reprod Apr 2018.

Atkinson et al. Pregnancy Hypertens. 2014 July;4(3):231.