Allen said that while exercise during pregnancy is definitely a good idea, these findings might be different if done with a different population. For example, American women are likely more ethnically diverse and have different average body-mass index levels.
But, in any case, Allen said, "Exercise should be encouraged for everyone who's healthy enough to do it. Exercise shouldn't be discontinued just because you're pregnant."
Allen added that research in the United States has also shown that women who exercise are less likely to have preterm deliveries.
Welch cautioned that as women progress in pregnancy, they should avoid any exercise that has them lay flat on their back, because this can restrict blood flow to both baby and mom. Also, contact sports are out, as is anything where falling might be likely, such as horseback riding.
He said he tells his patients to keep their heart rate to no more than 120 beats per minute during exercise. This allows you to get an aerobic workout, but isn't so much that it might shunt blood away from the baby, Welch explained.
Read more advice about exercise during pregnancy from the March of Dimes.
SOURCES: Robert Welch, M.D., chairman, obstetrics and gynecology, Providence Hospital, Southfield, Mich.; Steven Allen, M.D., chairman, obstetrics and gynecology, Scott & White Healthcare, Temple, Texas; October 2009 Obstetrics and Gynecology