Can I Do Strength Training During Pregnancy?

I’ve been a competitive athlete, and fitness is part of my identity and a source of balance for me. After my first child, I got back into strength training and CrossFit. Between work and taking care of my 2-year-old, these intense workouts have been as important to my mental health as my physical well-being. I’m now pregnant with number two and, according to Google, should not be doing heavy lifting, jumping, or inversions. I’m desperate not to abandon what I love doing and looking for a way to modify without giving up entirely.
—Strong Mama

I feel this letter. The best thing my midwife did for me in my second pregnancy (other than catching the baby) was to encourage me to keep running and to tell me to get a running belt to make it happen. I’m well aware that exercise isn’t for everybody, but there are also a lot of people for whom it’s a huge part of what makes them tick.

There is actually an increasing emphasis on the value of exercise in pregnancy. As this 2016 paper says: “As the health benefits of exercise are increasingly recognized, the traditional advice to rest during pregnancy has changed toward a more healthy and active pregnancy.” However: the advice to exercise is often followed with “but not too much.” It’s more of a pitch to be like the ladies on Bridgerton — a little pall-mall, a bit of fresh-air walking. But, you know, nothing serious.

From a mental-health standpoint, though, not all exercise is created equal. And if what you like is CrossFit, a brisk turn around the gardens isn’t going to cut it.

The reality is that, perhaps because the traditional advice for women was to rest, we do not have a lot of detailed research about strenuous exercise in pregnancy. Some work with elite athletes suggests that when their heart rate got extremely high — above 90% of maximum — there was evidence of fluctuations in fetal heart rate that could be concerning. But this is a sample of six elite athletes, and it’s not about lifting, jumping, or inversions.

There is plenty of anecdotal evidence documenting that women successfully continue CrossFit during pregnancy (here’s one interview study, and one set of reports, admittedly from a biased source). What we do not have is some large data set saying this is okay, or drawing any limits. We definitely deserve better data on this. But even if we had better data: the answer is likely to depend heavily on the individual and on where they are in pregnancy. Some lifting, yes. How much? Less clear.

My overarching thought: I hope you have an OB you like, and, if you do, I would talk to them about the value you are getting from CrossFit and what to look out for to know if you are overdoing it.