Exercise During Pregnancy: What the Research Actually Says

For generations, pregnant women were told to rest, to take it easy, to avoid exertion. The advice was well-intentioned but wrong. The current evidence, built over decades of research, is clear: moderate exercise during pregnancy is not just safe; it is beneficial for both mother and baby. The American College of Obstetricians and Gynecologists now recommends at least 20 to 30 minutes of moderate exercise on most, if not all, days of the week for healthy pregnant women.¹

What the Guidelines Say

The ACOG guidelines, updated in 2020, recommend that healthy pregnant women get at least 150 minutes of moderate-intensity aerobic activity per week. This can be walking, swimming, stationary cycling, or any activity that raises the heart rate without causing breathlessness. The "talk test" is a useful guide: if you can carry on a conversation while exercising, the intensity is appropriate. If you cannot, you are working too hard.¹

The guidelines also recommend muscle-strengthening activities at least twice a week. Yoga, Pilates, and light weight training are all appropriate. The key is to avoid activities with a high risk of falling or abdominal trauma, such as horseback riding, skiing, or contact sports.

The Benefits

The research on exercise in pregnancy is extensive and overwhelmingly positive. A 2017 meta-analysis in the British Journal of Sports Medicine reviewed 136 studies and found that exercise during pregnancy was associated with a reduced risk of gestational diabetes, preeclampsia, and preterm birth. Women who exercised gained less excess weight, had shorter labors, and were less likely to need a cesarean section.²

The benefits extend to the baby as well. Studies have found that babies of mothers who exercise during pregnancy have lower birth weights within the healthy range, better cardiovascular health, and potentially better neurodevelopmental outcomes. The baby is not being deprived of oxygen or nutrients; the body is remarkably efficient at prioritizing the baby's needs, and moderate exercise does not compromise fetal blood flow.

Safe and Unsafe Activities

Most activities are safe in pregnancy, particularly if you were doing them before you got pregnant. Walking, swimming, water aerobics, stationary cycling, and modified yoga are excellent choices. Running and jogging are fine for women who were already runners. Strength training with light to moderate weights is safe and beneficial. The key modifications are to avoid lying flat on your back after the first trimester (which can compress a major blood vessel), to avoid activities with a fall risk, and to stay hydrated.

Warning Signs to Stop

Stop exercising and contact your provider if you experience vaginal bleeding, dizziness, chest pain, calf pain or swelling, muscle weakness, or fluid leaking from the vagina. These symptoms are uncommon but warrant attention. If you have a high-risk pregnancy, including placenta previa, preeclampsia, or a history of preterm birth, your provider may recommend modified or restricted activity. Always discuss your exercise plans with your provider, particularly if you have any pregnancy complications.³

The Bottom Line

Exercise in pregnancy is one of the best things you can do for yourself and your baby. It reduces complications, shortens labor, improves mood, and helps with postpartum recovery. The old advice to rest was based on fear, not evidence. The new advice, grounded in decades of research, is to move. Walk, swim, stretch, lift. Your body is built for this, and the research says that moving it, gently and regularly, is one of the best gifts you can give your baby.