Is it safe to exercise during pregnancy?

How much is too much exercise during pregnancy?
BY STEPHEN PRESCOTT AND ADAM COHEN Published: June 25, 2013

Adam's Journal

My sister is an animal. And I mean that in the sweetest, most affectionate way that a big brother can speak of a younger sibling.

Ali was a four-sport star in high school. After a standout collegiate career, she traveled the world while playing tennis professionally for two years. For the next dozen or so years, her post-tennis life involved working out vigorously every day and running the occasional half-marathon or marathon.

The marathons and half-marathons dropped out of the picture when she became pregnant late last year. But as I witnessed firsthand on a family vacation earlier this month, even at seven-plus months, Ali continues to work out on a daily basis.

The length and intensity of these workouts have dropped, but by anyone but Ali's measure, they would still be considered intense. A typical session now consists of a four- or five-mile run at eight- to nine-minute-mile pace. She also continues to do things like canoeing and hiking.

I'm a pretty committed fitness enthusiast myself, but I grew concerned at the sight of my sister and my soon-to-be niece or nephew blowing by other joggers on a running trail. I know that it's healthy to exercise during pregnancy, but how much is too much? And do her workouts potentially risk inducing early labor or harm to her child?

Dr. Prescott prescribes

As a general rule, if you exercised before you were pregnant, it's healthy to continue. And even if you didn't, as long as you get the OK from your physician, staying active brings numerous benefits during pregnancy. It helps control weight gain, maintains cardiovascular health, prepares the body for childbirth, and even lessens the chances of developing preeclampsia and gestational diabetes, conditions that can be dangerous or even life-threatening to mothers and their unborn children.