BDO: What is the biggest misconception you’ve heard about exercising while pregnant?
Dr. Jamil: The biggest misconception that I’ve heard is that exercise during pregnancy can increase a woman’s risk for preterm labor or miscarriage. Neither of these assertions has been found to be true. One caveat however is that extreme exercise without proper hydration can increase a woman’s risk of dehydration. Dehydration does cause the pituitary gland to release a hormone called ADH (anti-diuretic hormone) that helps to prevent further water loss in the urine of someone who is dehydrated.
ADH however is structurally almost identical to oxytocin, the hormone that the pituitary gland creates to cause the uterus to contract during labor. So when a pregnant woman becomes dehydrated and her pituitary glands produces high level of ADH, the uterus can become “confused,” interpreting the elevated ADH levels as oxytocin and causing preterm labor. Preterm labor caused by dehydration, if not properly addressed, can obviously lead to preterm delivery. I’ve also had some patents express concern that exercises that require them to lift their arms over the heads increase the risk for a nuchal cord (i.e. the umbilical cord wrapping around the neck). This is also not true.
BDO: When should you shy away from exercise while pregnant?
Dr. Jamil: For the most part exercise during pregnancy is ok. However, if a woman has a preexisting medical condition, exercise may not be safe for her and she should consult with her doctor first. Women with asthma and with certain cardiovascular diseases (e.g., irregular heart rate, heart disease, etc.) should probably avoid exercise. This is in part because various hormones of pregnancy like estrogen, progesterone, etc. cause changes in both the respiratory and the cardiovascular system. These changes, especially when the respiratory and cardiovascular systems are being stressed during exercise can increase a pregnant woman’s risk for exercise related respiratory or cardiovascular morbidity.
For example, 33 percent of pregnant women with asthma will have worsening of their asthma during pregnancy. This is because progesterone in particular causes the smooth muscles around the airways to relax. With these muscles less active the airways can’t conduct air into and out of the lungs as effectively as they were prior to pregnancy. This will cause 33 percent of pregnant women to have a more poorly controlled asthma during pregnancy that obviously puts them and their unborn babies at increased risk for problems that result from suboptimal oxygenation during exercise.
BDO: For those who don’t exercise regularly (or at all), what are some simple ways to implement fitness into their daily regimen while pregnant?
Dr. Jamil: That’s a tough one. I will frequently encourage pregnant women who are beginners and who are looking to implement fitness into their life to join other groups of pregnant women doing the same thing. For example, my local YMCA has a “Pregnancy Yoga Class” that is open to all pregnant women. Doing something like this provides a nice support structure that makes it easier for a beginner to remain committed to the new regimen. I also encourage pregnant women to consider doing simple things like taking the stairs rather than the elevator at work, or to consider walking to work if they don’t work far from home.