In the early to mid-1900s, pregnancy was regarded as a state of confinement. It was believed that exercise should be discouraged due to a number of theories:
- Decreased uterine blood flow due to dehydration and blood being redirected to the muscles causing poor foetal growth
- Increased core temperature in the first trimester causing teratogenic effects
- Increased release of chemicals and hormones that could trigger preterm delivery
- Or increased risk of injury due to relaxin release and joint laxity
However, even though we need to take these theories into consideration, more current evidence suggests that exercise during pregnancy can be safe, and even beneficial in Women who are considered ‘low risk pregnancy”.
In 1985, the American College of Obstetricians & Gynaecologists (ACOG) released a position statement that claimed “Women who have previously engaged in regular physical activity may continue to do so with the following restrictions:
- Do not exercise for longer than 15 minutes
- Do not exceed a maternal heart rate higher than 140 beats per minutes
- And do not allow core temperature to rise above 38 degrees Celcius.”
The studies that followed this position statement found that these regulations may actually have been too conservative and hence a new position statement was released in 1994, which revealed that “Women who have previously exercised can continue mild to moderate exercise with no restrictions to heart rate and time.”
Then, in the late 1990s, there was an influx of research concerning the discussion around Gestational Diabetes and a new position statement was released in 2002 stating that “30 minutes or more of moderate-intensity exercise on most if not all days is recommended for all pregnant women in the absence of medical or obstetric complications”. This means that exercise can be safe and is beneficial for previously sedentary individuals. Furthermore, following medical review, exercise may still be recommended in the presence of medical or obstetric complications with supervision from a qualified healthcare professional.
A study by Bauer et al. (2010) showed that 99% of healthcare professionals (that included medical doctors, obstetricians and midwives) agreed that exercise during pregnancy is beneficial, however, 64% of these respondents were not aware of the abolition of the 1994 ACOG guidelines in regards to heart rate and time restrictions. The implications of this study bring me to the point that it may be a very long time before people are aware of the most recent ACOG committee opinion in 2015.
So, here are the most up-to-date guidelines regarding pregnancy and exercise according to ACOG committee opinion 2015:
- Women with uncomplicated pregnancies should engage in an aerobic and strength-conditioning exercise routine
- A moderate-intensity exercise program (equivalent to brisk walking or 13-14 “somewhat hard” on the Borg scale of perceived exertion) for at least 20-30 minutes per day (150 minutes per week) on most if not all days is recommended
- Physical activity in pregnancy has minimal risk and is beneficial to most women
- Some modifications to exercise may be necessary due to normal anatomic and physiologic changes and fetal requirements
- A thorough clinical evaluation should be conducted before recommending an exercise program to ensure that a patient does not have a medical reason to avoid exercise
- Obstetrician-gynecologists and other obstetric care providers (i.e. physios) should carefully evaluate women with medical or obstetric complications before making recommendations on physical activity participation during pregnancy
- Regular physical activity during pregnancy improves or maintains physical fitness, helps with weight management, reduces the risk of gestational diabetes in obese women, and enhances psychological well-being
In summary, exercise is safe and even beneficial for most women during their pregnancy. There are some conditions (such as gestational diabetes, morbid obesity and chronic hypertension) where an unsupervised exercise program poses a risk, however, provided with suitable health professional monitoring, an exercise program would be of benefit. It is imperative to attain Obstetrician and/or Gynaecologist clearance.