Similar to early parenting, pregnancy is a period characterized by an ocean of contradicting advice from family, friends, as well as health professionals and media.
Particularly confusing is the information regarding physical activity.
A strong tradition of recommending bed-rest and inactivity during pregnancy exists (and has contributed to excessive weight gain during pregnancy). However, the scientific foundation for this advice is questionable. A recent, comprehensive review of the physical activity guidelines for pregnant women was published last month in the Journal of American Medical Association, by Perales and colleagues. Using this source, in this blog, we summarize whether some commonly held beliefs around exercise during pregnancy are myths or truths.
1. Exercise in pregnancy can induce fetal stress in the baby and risks on the mother. FALSE! A recent robust meta-analysis has shown that moderate intensity activity from late in the first trimester to the end of term was not associated with any increased risk of preterm delivery or fetal stress for the baby or the mother.
2. A previously inactive woman should not start exercising during pregnancy: FALSE! A recent randomized controlled study has demonstrated that pregnancy is as good a time as any to begin exercising.
3. Women with chronic hypertension, gestational diabetes or obesity should refrain from exercising during pregnancy: FALSE. Moderate intensity aerobic and/or strength training has now been shown to be safe for women with these conditions.
4. The recommended volume of exercise for pregnant women is lower compared to that for non-pregnant women: FALSE! All pregnant women living without major medical or obstetric contraindication to exercise are encouraged by the American College of Obstetricians and Gynecologists (ACOG) to follow the same guidelines as those that are not pregnant (30 min of moderate-intensity physical activity, 5 days per week).
5. Contact sports and high-intensity exercise is to be avoided in pregnancy: TRUE! Intense exercise might reduce the blood flow to the placenta, and therefore exercising at more than 90% of your maximal heart rate is not recommended. Contact sports, hot yoga, exercises conducted lying with the face up, long distance running, heavy weight lifting are also not recommended, particularly from the second trimester onwards.
6. Pilates and Yoga are the best forms of exercise for pregnant women: FALSE!
While Yoga and Pilates provide psychological benefits, they do not appear to lead to measureable physical benefits in pregnancy.
7. It is best to stop being physically active and exercising in late pregnancy: FALSE! Many studies demonstrated that it is safe and beneficial to continue exercising (following the recommendations) until term (week 39).
In addition to clarifying these points, Perales et al., clearly highlight the benefits of exercise during pregnancy and provide easy to use exercise recommendations.
Benefits of exercising during pregnancy. There is a strong consensus of benefit for both the mother and the developing fetus. The major benefits of participating in the recommended exercise include the prevention of excess weight gain, as well as decreased risk of a variety of conditions such as maternal gestational diabetes, hypertension, Cesarean delivery, low back and pelvic girdle pain and urinary incontinence. Further, it lowers the risk to having a significantly large baby, or baby with breathing problems.
Recommendations for exercise in pregnancy.
To take part in moderate aerobic exercise such as walking, dancing or swimming for 20-30 minutes 3-5 times per week. Resistance band or body weight exercises involving large muscle groups are also safe to do for 15-20 minutes per day, 3-5 times per week. Combining both, low impact aerobic and strength exercises is highly recommended and can be safely practiced for 45-65 minutes, 3-4 times per week. If you are still unsure how intense the exercise should be just try the talk test: as long as you can maintain a conversation, you are not overexerting yourself.
While safe for most, exercising in pregnancy requires additional caution for some women, and is to be avoided by others (for example, in the presence of vaginal bleeding beyond the first trimester, significant heart disease, risk of premature labor, etc.). For more details, please refer to the ACOG guidelines, or consult a health practitioner.
In summary, overcautious beliefs in regards to exercise in pregnancy have resulted in the large majority of women being underactive during pregnancy. Robust research has now demonstrated that when guidelines are followed, exercise is safe and beneficial throughout pregnancy, both for the mother and the fetus. So, if you currently exercise and are pregnant, keep it up; if you have not exercised before, and wish to start, now is as good a time as any.
Ilaria Croci, Postdoctoral Research Fellow at CERG