In 2011, a runner here in Chicago gained some fame after completing the Chicago Marathon, then delivering her healthy full-term baby hours later. Having gone through the heartbreak of years of infertility, I admit I felt both admiration with this woman’s accomplishment and annoyance that she would seem to take a chance with her soon-to-be-born baby’s health.
But did this person accomplish her feat while taking unnecessary or selfish risks? As it turns out, probably not. This article is a review of current recommendations about exercise during pregnancy. Please, dear reader, remember that this article is not medical advice in any way. If you are pregnant, please review your exercise program in detail with your obstetrician! Every woman and every pregnancy is unique and there are specific risk factors that may lead an obstetrician to prohibit or heavily modify an exercise program during pregnancy.
It wasn’t long ago when pregnancy was treated as a disabling illness. Women were told to be inactive and were given lengthy hospital stays with extended bedrest before and after delivery. Now, we know that this approach is not ideal for most pregnant women. In fact, regular exercise, before, during, and after pregnancy, enhances health for most women. Benefits of exercise during pregnancy include :
- Reducing backaches, constipation, bloating, and swelling
- Possibly preventing or treating gestational diabetes
- Increasing energy
- Improving mood
- Improving posture, muscle tone, strength, and endurance
- Improving sleep
- Possibly improving the ability to cope with labor
- Improving the capacity to get back in pre-pregnancy shape
Similar to recommendations for most healthy people, pregnant women (after having consulted with their obstetricians) are encouraged to exercise at least 30 minutes on most, if not all, days of the week.
Pregnancy has specific effects upon the body that can impact exercise. These effects include increased mobility of joints, which can increase the risk for injury, and extra weight in front of the body, which shifts the center of gravity and can lead to back pain and decreased balance. Additionally, the extra weight (and increased volume of distribution of blood) leads to increased work from exercise. Because of these effects of pregnancy on exercise, it is best to avoid activities that demand a lot of jumping, jarring motions, or quick changes in direction and to lower expectations of intensity of exercise. Also, after the first trimester, avoid exercise while lying supine or prone.
Preferred exercise during pregnancy includes:
- Cycling (preferably on a stationary bike, especially during the second and third trimesters, since balance can be affected)
- Running (primarily for women who were runners before pregnancy)
Exercise to be avoided during pregnancy includes:
- Downhill skiing (because of decreased balance, the risk of physical injury, and the risk of altitude sickness)
- Contact sports (including hockey, basketball, and soccer)
- Scuba diving (because of the risk of decompression sickness)
Exercise during pregnancy does create specific risks to developing fetuses. One of these risks is poor growth. There are increased caloric needs during pregnancy (inactive pregnant women generally need 3000 calories per day) and these needs are made more complex by burning extra calories with exercise. Therefore, it is important to follow weight and fetal development closely and make caloric adjustments accordingly. Women who normally exercise at a high level, such as elite and professional athletes, should be especially careful to maintain good caloric intake.
Aside from developmental risks over time, there are risks to fetuses during exercise, itself. These risks include overheating, dehydration, and decreased blood flow to the fetus. These are important risks, but they can generally be managed with the following recommendations:
- Avoid exercise in hot and humid weather
- Never exercise with a fever
- Drink plenty of water and sports drinks
- Avoid exerting over 90% of exercise capacity (as defined as 90% of maximal maternal heart rate)
Most of us never push ourselves to 90% or more of maximal heart rate, but elite athletes do. This last recommendation is based on a study of pregnant elite athletes who demonstrated fetal bradycardia, high umbilical artery pulsatility index, and reduced mean uterine artery volume blood flow when they exercised more than 90% of maximal maternal heart rate. These findings appeared to be replicated in a separate study in which the pregnant athletes also exerted over 90% of maximal maternal heart rate. In other words, at this level of exercise, the developing fetuses were stressed a great deal.
Warning signs to stop exercising and seek help include:
- Vaginal bleeding or leaking of fluid
- Dizziness or feeling faint
- Shortness of breath
- Chest pain
- Muscle weakness
- Calf pain or swelling
- Uterine contractions
- Decreased fetal movement
Pregnancy should not be viewed as an interruption to a fit lifestyle. In fact, exercise can be an important part of having a successful, healthy pregnancy. However, there are also important risks and warning signs to consider. An obstetrician is the best resource to help pregnant women balance benefits and risks while planning an exercise program. This statement is especially true for elite and professional athletes, who may need to give extra attention to such issues as caloric needs, core body temperature, hydration status, and peak heart rate.
Published April 11, 2015
Artal R and O’Toole M. Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period. Br J Sports Med. 2003;37:6-12.
Salvesen KA, Hem E, and Sundgot-Borgen J. Fetal wellbeing may be compromised during strenuous exercise among pregnant elite athletes. Br J Sports Med. 2012 Mar;46(4):279-283.
Szymanski LM and Satin AJ. Exercise during pregnancy: fetal responses to current public health guidelines. Obstet Gynecol. 2012 Mar;119(3):603-610.
Szymanski LM and Satin AJ. Strenuous exercise during pregnancy: is there a limit? Am J Obstet Gynecol 2012 Sep;207(3):179e1-179e6.