You would be surprised at the number of answers that are given to this question. The traditional thought was a categorical NO, but in the past several years views have begun to change. The American College of Obstetricians and Gynecologists has changed their tune with regard to exercise during pregnancy as of 2002. So let’s take a look at the question a little closer.
Will it do me any good to exercise when I am pregnant? The short answer is yes. It appears that regular exercise improves fitness (Cochrane review 2010) and it decreases the risk of having an overly large baby (Obstetrics and Gynecology 2009). Additionally it decreases the likelihood of gestational diabetes (Diabetes Care 2011) and for women who have gestational diabetes is appears to improve their diabetes control (Diabetes 1991 and American Journal of Obstetrics and Gynecology 1989). It appears that exercising regularly may decrease some of the third trimester discomforts (Medical Science of Sports Exercise 1995) and daily yoga decreases labor discomfort (Complimentary Therapies in Clinical Practices 2008) and reduces stress (International Journal of Gynaecology and Obstetrics 2009).
Are there any problems with exercising while pregnant? There are some theoretical concerns regarding the potential to decrease the blood supply to the placenta and baby, preterm labor and potential trauma. Studies looking into this have yielded varying results. Here are several studies that look at the effects of exercise and possible effect of low birth weight (here, here, here, here, and here). Some studies show that exercise does not change birth weight (here, here, here, here, and here). And yet another shows that it might increase birth weight (here). In a large study that reviewed 18 prior studies it did not appear that exercise had a significant effect on maternal weight gain, birth weight, length of pregnancy, length of labor, or scoring of the infant at birth (Medicine and Science in Sports and Exercise 1991).
What do I need to know to exercise safely? There are some very clear reasons NOT TO exercise and these are absolute: Pregnancy induced hypertension, Premature rupture of membranes, Incompetent cervix (or having had the surgery to keep the cervix closed), persistent second or third trimester bleeding, a baby that is not growing very well, preterm labor in this or a prior pregnancy (ACOG 2002). Additionally, if you have heart disease, uncontrolled high blood pressure, uncontrolled kidney disease, profound anemia, or uncontrolled diabetes you are probably better off without the exercise while you are pregnant. Generally the exercise you were doing prior to pregnancy can be continued. Here are some specific guidelines from DynaMed:
- sedentary women - walking, bicycling, stair climbing, aerobic dance, water aerobics or swimming for 65-75% of maximum heart rate for 30 minutes 3 times/week
- recreational athletes/regular fitness exercisers - same as above plus running/jogging, dance, tennis at 65-85% of maximum heart rate for 30-60 minutes 3-5 times/week
- elite athletes - same as above plus some competitive activities depending on gestational age at 75-85% of maximum heart rate for 60-90 minutes 4-6 times/week
And of course, it goes without saying that you should probably avoid certain high risk activities such as contact sports (boxing, field hockey, football, rugby, ice hockey, martial arts, rodeo, soccer, wrestling), high risk sports (scuba diving, hang-gliding, parachuting, rock climbing, power lifting) and overly strenuous exercise that might lead to dehydration or hyperthermia.