Is it OK to exercise at a high altitude while pregnant?

Q: I am in my first trimester and recently read that pregnant women should not exercise at altitudes higher than 6,000 feet. I live at 5,300 feet and frequently hike at 8,000 feet. Should I stop?

A: There is evidence that exercise at elevations higher than 6,000 feet may cause changes in heart rate, lung capacity and other cardiopulmonary measures that could potentially cause pregnancy complications. But that research does not necessarily apply to women who are used to exercising at higher elevations. I feel that your regular hikes probably are fine (but do check with your doctor). Still, I recommend modifying the intensity in your second and third trimesters. Be aware of overexertion; symptoms include uterine contractions, excessive perspiration and increased shortness of breath.