What people believe
The fear that exercise during pregnancy could cause miscarriage, preterm labour, or harm to the baby is widespread. Many pregnant women reduce or stop exercising entirely after a positive test, often encouraged by family members who view any physical exertion as risky. The belief is reinforced by outdated advice that once recommended bed rest for many pregnancy complications — a practice that has itself been largely debunked.
What the evidence says
ACOG's position is clear: women with uncomplicated pregnancies should be encouraged to engage in aerobic and strength-conditioning exercise before, during, and after pregnancy. The recommendation is at least 150 minutes per week of moderate-intensity aerobic activity.1
Exercise during pregnancy is associated with reduced risk of gestational diabetes, preeclampsia, excessive gestational weight gain, caesarean delivery, and postpartum depression.1 A 2019 systematic review and meta-analysis of 17 randomised controlled trials found that prenatal exercise reduced the odds of gestational diabetes by 38% and preeclampsia by 41%.2
There is no evidence that moderate-intensity exercise increases the risk of miscarriage, preterm birth, or low birth weight in uncomplicated pregnancies.1 Activities generally considered safe throughout pregnancy include walking, swimming, stationary cycling, low-impact aerobics, yoga (modified for pregnancy), and strength training with appropriate modifications.
Activities to avoid include contact sports, activities with a high risk of falling (skiing, surfing, horseback riding), hot yoga or hot Pilates, scuba diving, and any exercise performed lying flat on the back after the first trimester (due to compression of the inferior vena cava).1
What to do instead
Unless your provider has identified a specific contraindication — such as placenta praevia, preeclampsia, cervical insufficiency, or certain types of preterm labour risk — exercise is not just safe, it is recommended. Start with what feels manageable and aim for consistency rather than intensity.
If you were not exercising before pregnancy, begin with 10–15 minutes of low-intensity activity and build gradually. If you were active before pregnancy, you can generally continue your routine with appropriate modifications.