Is CrossFit safe during pregnancy?

What does the evidence say about CrossFit during pregnancy?

1. In a study of 60 pregnant athletes doing treadmill and cycling high-intensity interval protocols, fetal heart rate stayed at a normal average of roughly 141 to 149 beats per minute during recovery, and although a handful of women had a brief episode of fetal heart rate dropping or spiking that ended the session, researchers concluded highly active women can do multiple high-intensity intervals without apparent harm to fetal well-being. 1
2. In 48 pregnant athletes at 26 to 35 weeks performing heavy sumo deadlifts, bench press, and incline bench press at about 76 percent of their one-rep max, fetal heart rate stayed within the normal 110 to 160 beats per minute range throughout, leading researchers to conclude that highly active women, especially those with resistance training experience, can safely include heavy lifting and on-your-back exercises without jeopardizing fetal well-being. 2
3. Using 3D Doppler ultrasound in 22 pregnant women lifting an average of 30 pounds, with up to 50 pounds allowed, researchers found placental blood flow during the lift was slightly higher than at rest, not lower, concluding that moderate-to-heavy resistance training, including the breath-holding Valsalva effort it involves, did not reduce blood flow to the placenta. 3
4. In pregnant athletes doing repeated 5-minute high-intensity running intervals, core body temperature rose by about 1.2 degrees Celsius on average but topped out at 38.76 degrees Celsius, staying under the 39 degree Celsius level researchers watch for heat-related risk, which the authors attribute to pregnancy's own enhanced heat-regulation changes. 4
5. A review of 22 institutional exercise guidelines found real disagreement on high intensity specifically: the IOC has cautioned that high-intensity training can be harmful to the fetus, while newer guidelines from Canada, Australia, and Poland allow women with a regular exercise background to continue vigorous activity if the pregnancy is healthy, with one group capping vigorous sessions at three per week in the third trimester. 5

Is CrossFit safe in each trimester?

• First trimester. There's no blanket ban on CrossFit this early, and if you were doing it before pregnancy, most guidelines support continuing at a similar intensity while your body adjusts. This is a good time to tell your coach you're pregnant so workouts can start getting individually scaled rather than waiting until you're visibly showing.
• Second trimester. This is when most of the direct research sits: studies of pregnant athletes performing heavy deadlifts, bench press, and high-intensity interval circuits in the late second trimester found fetal heart rate stayed in the normal range afterward. Supine, on-your-back movements are still worth limiting as your uterus grows, since lying flat can compress a major vein.
• Third trimester. Balance, joint laxity, and a shifting center of gravity make fall-risk movements like box jumps, heavy overhead lifts, and kipping pull-ups the first things most coaches scale back late in pregnancy, even for very experienced athletes. Some guidelines cap vigorous sessions at about three per week in the third trimester.

CrossFit movements: what the research and guidelines say