There's not much room to work out when you're inside your mother's womb, but a new study suggests that babies whose mothers exercise get benefits to their cardiovascular systems.

Researchers used devices to track fetal development and movements such as breathing and hiccups in pregnant women between 20 and 35 years old. The women were put into two groups -- those who exercise for 30 minutes at least three times a week and those who do not.

The researchers found that near full-term, fetal heart rates were significantly lower in mothers who work out.

The authors of the study said they hope to use the news that parental exercise helps babies as a way to improve the health of children born to women at risk for gestational diabetes.

The research was conducted at Kansas City University and the University of Kansas Medical Center.