In 1949, the U.S. Children’s Bureau issued a standard recommendation for prenatal physical activity that advised, in the absence of maternal complications, that pregnant women could continue housework, gardening, daily walks, and swim occasionally, but should avoid sports participation (4). Women were told that they must limit physical activity primarily because of fears surrounding the possibility of a decreased oxygen supply to the baby, as well as other potential health risks. Across time, research has demonstrated that exercise during pregnancy does not harm the fetus but provides benefits for the mother and the baby.
In 1985, the American College of Obstetrics and Gynecology (ACOG) published the first exercise-specific guidelines for pregnant women. Based on limited research in exercise and pregnancy, the guidelines were rather conservative. Women were advised not to exceed a heart rate of 140 BPM during activities and were discouraged from performing vigorous activity for more than 15 minutes at a time. As evidence demonstrating the benefits of exercise during pregnancy continued to emerge, ACOG removed the 140 BPM limit in 1994, provided more specific guidelines in 2002, and reaffirmed these guidelines in 2009. In 2008, the U.S. Department of Health and Human Services published the first pregnancy-specific guidelines that followed recommendations for healthy adults: “healthy women who are not already highly active or doing vigorous-intensity activity should get at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity per week during pregnancy and the postpartum period. Preferably, this activity should be spread throughout the week” (7).
Physical activity and reproduction are normal parts of life, and for healthy women, combining regular exercise and pregnancy appears to benefit both mother and baby (3). Research studies evolving during the past 50 years now provide sufficient data showing that it is safe and important for a pregnant woman to continue an exercise regimen or even start exercising. There is currently abundant empirical evidence to support the promotion of moderate prenatal physical activity for maternal health benefits. According to ACOG (1), a healthy woman with a normal pregnancy may continue a regular exercise program or begin a new exercise program.
However, what has not changed across the years is obtaining physician approval. When a woman learns that she is pregnant, the first thing she should do is seek physician approval to exercise. Generally, there is no reason to avoid exercise during this period, but a physician might advise a woman not to exercise for reasons such as some forms of heart and lung disease or cervical problems (5). After physician approval, a woman can then seek guidance from a qualified fitness professional to help design an appropriate exercise regimen.
EXERCISE BENEFITS DURING PREGNANCY
During pregnancy, exercise can provide a number of pregnancy-specific health benefits, in addition to the well-known exercise benefits for the general population (6). Pregnancy-specific benefits include:
- Preventing gestational diabetes especially in individuals with a body mass index >33
- Decreasing the risk of preeclampsia
- Having babies within normal birth weight
- Preventing excess maternal weight gain
Regular activity also helps a woman stay fit during pregnancy, may improve the woman’s ability to cope with labor, and lessen the symptoms of postpartum depression. Participating in an exercise program will help a woman get back in shape after the baby is born and enhance her progressive return to prepregnancy weight.
RECOMMENDATIONS FOR EXERCISE DURING PREGNANCY
In the absence of medical contraindications or obstetric complications, pregnant women can follow physical activity guidelines for healthy adults and pregnancy-specific recommendations (1,5,7). However, it is important for women to maintain an open communication with their physicians regarding physical activity patterns to ensure healthy progression of the pregnancy.
Sedentary women can start being physically active. Previously sedentary women can begin an exercise program and gradually increase it across time to target guidelines for adults. Walking can be a great option for women to ensure that the activity is not too strenuous. A woman should be able to maintain conversation during the activity. If she is out of breath, intensity should be decreased.
Previously active women can stay active. For women who are continuing their regular exercise regimen during pregnancy, exercise intensity should not exceed prepregnancy levels and should be modified as needed. It is important to listen to your own body, be aware of contraindications, and know when to take a break.
No upper limits for intensity. Women accustomed to high-intensity activities before becoming pregnant can continue their activity. This means that women can exercise above 140 BPM because this is no longer a limitation based on updated ACOG guidelines. For example, a runner can continue her workouts if no contraindications are present and she maintains an open communication with her health care provider. However, when comparing guidelines from different countries, guidelines are not unanimous regarding upper limits for vigorous-activity levels during pregnancy.
Adjust activity type as needed. Swimming and stationary cycling are appropriate non–weight-bearing exercises and are recommended. Weight-bearing exercises are similarly beneficial as long as they are comfortable. Walking, jogging, and low-impact aerobics programs are appropriate weight-bearing exercises. It is recommended, however, that activities relying on balance, such as bicycle riding, should be avoided, especially during the second and third trimesters because of changes in balance and the risk of falling. Contact sports should be avoided because of the possibility of abdominal trauma.
Swimming and stationary cycling are appropriate non–weight-bearing exercises and are recommended. Weight-bearing exercises are similarly beneficial as long as they are comfortable. Walking, jogging, and low-impact aerobics programs are appropriate weight-bearing exercises. It is recommended, however, that activities relying on balance, such as bicycle riding, should be avoided, especially during the second and third trimesters because of changes in balance and the risk of falling. Contact sports should be avoided because of the possibility of abdominal trauma.
Modify resistance training workouts. There is a hesitation in recommending strength training for pregnant women because of unknown effects on the fetus. Heavy lifting could reduce blood flow in the uterine and umbilical vessels. Valsalva maneuver is a concern. Consulting a physician is recommended. In general, women should not perform activities that they are not accustomed to but continue with familiar activities. As with other forms of activity, intensity should be modified as pregnancy progresses.
Avoid supine position after first trimester. Lying on the back can pose a risk of decreased cardiac output and restricted blood flow to the fetus. A good alternative is to stay in a seated position while performing activities, especially during strength training.
Watch the altitude. Exertion below 6,000 feet altitude seems to be safe. However, it is important to be aware of altitude sickness. In such situations, descend and seek medical help.
Stay hydrated and watch the heat index. Temperature regulation is highly dependent on hydration and environmental conditions. Exercising pregnant women should ensure adequate fluid intake before, during, and after exercise, wear loose-fitting clothing, and avoid high heat and humidity to protect against heat stress.
Know signs and symptoms to stop exercising. Dizziness, vaginal bleeding, and decreased fetal movement are just a few important signs and symptoms to be aware of.
WORKOUT TIPS FROM A FITNESS PROFESSIONAL
According to Julieann Harris, ACSM Certified Personal Trainersm, there is more to maintaining an exercise program beyond the recommended guidelines (2). Harris, an endurance runner, realized this when she became pregnant. Experiencing pregnancy from the perspective of the fitness professional helped her understand the challenges during this period that can impact an exercise routine. In conjunction with the recommended guidelines, Harris provides the following tips that fitness professionals can use and integrate into an exercise program for pregnant clients.
- Track morning sickness. Tracking morning sickness helps a woman understand what times of day she experiences symptoms. Exercise workouts can be modified and timed based on when a woman typically does not experience symptoms. Fitness professionals need to be flexible in scheduling and discussing with clients the best time of day to train based on their symptoms.
- Decrease exercise intensity. Clients accustomed to high-intensity workouts might feel nauseous and sick after a workout. Decreasing exercise intensity may eliminate these symptoms. Fitness professionals should develop exercise programs that modify the intensity levels of each session. Clients will stay motivated.
- Understand weight gain. Weight gain is a natural occurrence during pregnancy and can be one of the most difficult aspects of the 9 months for a woman to accept. In conjunction with a woman’s physician, help the client understand why she is gaining weight and what is an acceptable increase based on guidelines and her current health status.
In general, knowledge about exercise and pregnancy is included in certifications that cover core competencies for working with exercise programs for healthy individuals or those who have medical clearance to exercise, as well as special populations. Courses for special populations include the pathophysiology on a range of conditions such as cardiovascular, pulmonary, metabolic disease, older adults, and pregnancy. Examples of appropriate certifications include the ACSM Exercise Physiologist Certification, ACSM Certified Personal Trainer®, and the American Council on Exercise Therapeutic Exercise Specialty Certification.
Exercise and regular physical activity during pregnancy are not only beneficial but important and will help a woman maintain her health and may improve her ability to cope with labor (1). Regular activity while pregnant also can make it easier for a woman to achieve her physical fitness goals after the baby is born. Fortunately, the antiquated guidelines of the past are now history. Current research provides valuable data to assist the qualified fitness professional in developing a safe, relevant, and effective program for a woman so she can continue to exercise or begin exercising while pregnant.
4. Downs DS, Chasen-Taber L, Evenson KR, Leiferman J, Yeo S. Physical activity and pregnancy: past and present evidence and future recommendations. Res Q Exerc Sport
[Internet]. 2012; 83(4): 485–502. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3563105/
© 2016 American College of Sports Medicine.
5. Evenson KR, Barakat R, Brown W, et al Guidelines for physical activity during pregnancy: comparisons from around the world. Am J Lifestyle Med
. 2014; 8(2): 102–21.