What's The Protocol For Exercising While Expecting?

Tennis great Serena Williams announced Wednesday that she's 20 weeks pregnant, which means that she was expecting her first child when she won the Australian Open in January. That made us wonder: How much exercise is safe during pregnancy?

A recent study in the Journal of the American Medical Association concluded that exercising, in most cases, is good for mothers and their babies. But that also leaves some women questioning whether there's such a thing as too much.

For answers, Here & Now's Meghna Chakrabarti talks with Dr. Jessica Shepherd, a professor of obstetrics and gynecology at the University of Illinois Chicago. Shepherd (@JShepherd_MD) is also founder of Her Viewpoint, an online forum for women's health issues.