Traditionally women were told to rest and relax when they became pregnant for the health of both mother and baby. However, all this changed in 1985 when the first guidelines for prenatal exercise were developed. Based on three subsequent decades of extensive research, we now know that mothers derive significant health benefits from exercising during pregnancy. Leading an active lifestyle can prevent excessive gestational weight gain, reduce the risk of developing gestational diabetes and improve maternal tolerance to labour.
In contrast, the beneficial effects of maternal exercise on fetal health are still being discovered. Previous hesitations towards maternal exercise were in part based on small studies in athletic populations, which suggested that maternal exercise may cause smaller babies. However, a recent meta-analysis from the Program for Pregnancy and Postpartum Health (PPPH) helped to dispel this myth. After looking at 28 studies of 5,322 women randomized to either exercise or no exercise in the last two decades, we found that prenatal exercise reduced the risk of having a large baby by 31% without increasing the risk of having a small or earlier baby. In addition, women who exercised had a 20% decreased risk of having a cesarean section. These findings are extremely important because babies who are born large are more likely to be heavier through childhood and into adulthood, and are at higher risk for developing chronic diseases such as diabetes later in life. Leading an active lifestyle during pregnancy can be beneficial for both mother and baby!
Today, guidelines for exercise during pregnancy have been updated and expanded to provide recommendations for women of differing fitness levels, ages and body sizes. The current Canadian Guidelines for Exercise During Pregnancy were jointly developed by the Society of Obstetricians and Gynaecologists of Canada (SOGC) and the Canadian Society for Exercise Physiology (CSEP). These guidelines include the PARmed-X for Pregnancy which provides the most up-to-date information about aerobic exercise and muscular conditioning, as well as important tips and precautions to ensure safe participation in physical activity. Prior to starting or continuing an exercise program during pregnancy, all women should consult with their health care provider. The PARmed-X for Pregnancy, as well as other information, are available at exerciseandpregnancy.ca under "resources".
The current guidelines recommend that all pregnancy women without contraindications to exercise be physically active. Following clearance from their health care professional, women are encouraged to exercise 3-4 times per week using large muscle groups where risk of falling or impact to the belly is minimized (e.g., walking, swimming, stationary bicycling etc). The current guidelines also provide lower target heart rate zones equivalent to a moderate walk which have been demonstrated to be beneficial at improving blood sugar control, controlling gestational weight gain and increasing fitness. These guidelines also include higher target heart rate zones based on age for fitter women / regular exercisers who have been medically pre-screened. This allows active women to continue to exercise at higher intensities which have been shown to be both safe and beneficial for both mother and baby. At all intensities, the "talk test" is an important measure of whether intensity is too high as women should be able to carry on a conversation during exercise.
Women who were not active before becoming pregnant can begin to exercise in the second trimester, after the discomforts of the first trimester have passed. This can involve starting with 15 minutes of exercise plus 5 minutes of warm up and cool down, increasing gradually over the course of pregnancy. Women who were active prior to pregnancy are recommended to continue to exercise under the guidance of their maternity health care provider.
Despite the demonstrated benefits of maternal exercise during pregnancy, only 15% of women in Alberta (and around North America) meet current guidelines. Exercise can be performed in many enjoyable ways. Get your partner or children involved and make it a family outing. Even a gentle walk 3 times per week can be very beneficial for pregnant women!
While the majority of maternity health care providers do recommend women be active during pregnancy, the focus is often on how much exercise is too much while less attention is given to how much activity is too little. Practitioners can find more information on the SOGC/CSEP Clinical Practice Guidelines at sogc.org or csep.ca. Pregnant women are encouraged to discuss the positive benefits of prenatal exercise with their healthcare providers. For more information on ongoing research in this area, please visit exerciseandpregnancy.ca.