Active Voice: Why Should Pregnant Women Exercise?
By Lanay Mudd, Ph.D.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Dr. Mudd is an assistant professor in the department of kinesiology at Michigan State University. With a background in both kinesiology and epidemiology, her research focuses on maternal and child health benefits of physical activity during pregnancy. In this commentary, Dr. Mudd, an ACSM member, presents her views associated with the research which she and her colleagues published in the February 2013 issue of Medicine and Science in Sports and Exercise® (MSSE).
“It’s six o’clock, so should I sit on the couch and watch some TV or fit in a quick walk before dinner?” For many pregnant women, the answer is automatic – “I’m tired and I’m pregnant. I deserve to relax. What’s on TV?” Yet, research conducted over the past 18 years indicates that the woman who laces up her sneakers instead, can expect a healthier pregnancy and a healthier baby.
In the past, most viewed pregnancy as a time to rest and gain weight in order to ensure a healthy delivery. The first physical activity guideline, published by the American College of Obstetricians and Gynecologists (ACOG) in 1985, even encouraged women to limit vigorous physical activity and keep their exercise heart rates below140 beats per minute. Unfortunately, while hundreds of studies have since shown benefits of physical activity during pregnancy and the guidelines have been subsequently updated many women and healthcare providers cling to this 140 limit. The most recent U.S. Dept. of Health & Human Services guidelines for physical activity during pregnancy state that women who are not already active should get at least 150 minutes per week of moderate intensity aerobic activity, and that those who are habitually more active may continue their normal routines provided they communicate openly with their healthcare provider. International guidelines in Canada, Denmark and Norway are similar.
Since pregnant women are now encouraged to be active, many may wonder “What benefits can I expect if I choose walking over TV?” In MSSE, our recently published review of the international evidence suggests that women who are active either before or during pregnancy have a lower risk of developing gestational diabetes and hypertensive disorders during pregnancy. In addition, they are more likely to stay within the recommended weight gain range. Furthermore, compared to inactive women, active women are less likely to deliver big babies (more than nine pounds) and a few small studies suggest that their children are less likely to be obese at two to five years of age.
These conclusions are encouraging and reinforce the need for healthcare and fitness professionals to promote physical activity to pregnant women. The question now is “How much and what type of activity do I need to see these benefits?” While the current literature can’t directly answer these questions, performing the recommended 150 minutes per week of moderate aerobic physical activity is a good place to start.
Most of the current evidence is based on observational designs where the majority of women who are active during pregnancy were also active before pregnancy. Thus, we can’t say whether women who choose to start walking during pregnancy will see the same health benefits. More intervention studies are needed to answer that question. If the same benefits are found, promotion of physical activity during pregnancy with previously inactive women could prove a vital part of improving the health of women and children worldwide.