Canadian Guidelines for Exercise in Pregnancy

Abstract

The need for guidelines for exercise during pregnancy and the postpartum period was stimulated during the early 1980s when active women of the “baby boom” generation became interested in whether it was safe to continue their active lifestyles during pregnancy. As a result of the strong demand for information, important questions were raised concerning the risk/benefit ratio of such exercise. Postulated risks included the possibility that the fetus may be forced to compete with contracting maternal skeletal muscle for oxygenated blood flow (leading to fetal hypoxia and distress), essential substrates (leading to fetal growth restriction), and heat dissipation (leading to fetal hyperthermia and potential teratogenic effects). Concern was also expressed that exercise may increase the chance of early miscarriage, spontaneous abortion, and premature labor, as well as chronic fatigue and musculoskeletal injury. Putative benefits included maintenance of prenatal aerobic and musculoskeletal fitness levels, prevention of excessive maternal weight gain, facilitation of labor and recovery from labor, promotion of good posture, prevention of gestational glucose intolerance and low back pain, and improved psychological adjustment to the changes of pregnancy. As a result of the conflict between these postulated benefits and risks, the idea that a dose-response relationship existed between the quantity and quality of exercise and maternal/fetal well-being quickly emerged (Fig. 1). The concept that exercise is safe for some pregnant women but not others also led to the need for absolute and relative medical contraindications to exercise and the need for medical screening by a qualified health care provider before engaging in fitness training after becoming pregnant. As a result of a lack of scientific information, early guidelines for exercise during pregnancy were necessarily conservative and based primarily on common sense and Note: A copy of the Physical Activity Readiness Medical Examination for Pregnancy can be obtained from the Internet at: www.csep.ca/forms.asp Correspondence: Larry A. Wolfe, PhD, School of Physical and Health Education, Queen’s University, Kingston, Ontario K7L 3N6, Canada. E-mail: wolfel@post. queensu.ca CLINICAL OBSTETRICS AND GYNECOLOGY Volume 46, Number 2, 488–495 © 2003, Lippincott Williams & Wilkins, Inc.