Physical Activity during Pregnancy: Is It Wise?

Abstract

In this issue of the Canadian Journal of Diabetes, Back et al. (1) look at physical activity and nutritional intake of pregnant First Nations women living both in remote communities and in urban settings, and compare them to Caucasians living in urban settings. These authors found that physical activity is lower in both First Nations communities compared with the Caucasian urban women and that nutritional intake needed improvement, especially in the First Nations women living in rural communities. This study raises the question: “Should women be physically active during pregnancy?” In the past many believed that physical activity during pregnancy was harmful and should be avoided. The 1985 American College of Obstetrics and Gynecology (ACOG) Exercise During Pregnancy guideline stated “pregnant women should stringently limit the type, duration and intensity of their exercise tominimize both fetal andmaternal risk.” (2). Early studies focused on high-intensity activities and often failed to differentiate work-related activity from leisure activity. Since then, however, studies of moderate physical activity have not demonstrated adverse pregnancy outcomes. More recent guidelines from the Centre for Disease Control and Prevention (CDC) and ACOG recommend “30 minutes or more of moderate intensity exercise per day for most days of the week, in the absence of medical or obstetrical complications” (3,4). Guidelines released jointly by the Society of Obstetrics and Gynecology Canada and the Canadian Society of Exercise Physiologists in 2002 recommended that “all women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy” (5). Some absolute and relative contraindications were cited, and details can be found in the guidelines (5). Given that prior guidelines preached caution, one can reasonably ask why women should be “encouraged” to exercise during pregnancy? Studies of moderate exercise have not found adverse maternal or neonatal outcomes and have even suggested benefit. These reported benefits may be especially prudent in women such as our First Nations women, who are obese and at risk for numerous complications including preeclampsia, gestational diabetes mellitus (GDM) and macrosomia. Three case-control studies have found that physical activity reduced the rates of preeclampsia (6e8). In a case-control study of Canadian women, physical activity during the first 20 weeks of pregnancy reduced the risk of pre-eclampsia