We don't yet know the best way for pregnant women to exercise—how hard, how often, or what kind of support helps most—and we also need to understand if working physically while pregnant affects the mom and baby's health.

Being active during pregnancy is generally safe and helps most women feel better, stay fit, manage their weight, lower their chance of getting gestational diabetes (especially if they're overweight), and feel less stressed — so doctors often recommend it for healthy pregnancies.

Even when pregnant women with a normal weight are given exercise programs or motivation tips, most still don't get enough physical activity during pregnancy — they're still moving less than the recommended amount each week.

If a woman keeps exercising at the same level she did before getting pregnant, she’s less likely to run into pregnancy-related health problems than if she cuts back on exercise.

Working out while pregnant doesn't make it more likely for a mom to lose the baby, have the baby too early, or have a baby with low weight — it's generally safe for most pregnant women.

For healthy pregnant women who aren't very active, doing structured exercise three times a week plus some coaching about staying active doesn't seem to help them gain less weight by the time they give birth, compared to just getting regular prenatal care.