Women at low-risk pregnancy are encouraged to do at least 150 minutes of moderate physically activity per week or 20-30 minutes per day (ACOG, 2015). It is safe for female athletes and other women who have been physically active before pregnancy to largely maintain their training habits, while inactive women are recommended to gradually add exercise into their routine for their own health and for the health of their baby (ACOG, 2015; da Silva, Ricardo, Evenson, & Hallal, 2017). Nevertheless, it has been reported that as few as 5-15% follow these recommendations (Gjestland, Bø, Owe, & Eberhard-Gran, 2013; Nascimento, Surita, Godoy, Kasawara, & Morais, 2015), and that more than half of women interrupt practicing physical exercise due to pregnancy (Nascimento et al., 2015).
Benefits of exercise during pregnancy
Given the physical demands of delivery it makes good sense to be fit for delivery (Sagedal et al., 2013). There are several health benefits of exercise during pregnancy for both mother and child (Figure 1) including reduced excessive weight gain, reduced risk of gestational diabetes, hypertension and macrosomia – all conditions linked to increased incidence of childhood obesity. Despite these important effects of physical exercise, most physicians are not instructing their sedentary pregnant patients to exercise (McGee et al., 2018).
Concerns associated with exercise during pregnancy
Even with abovementioned health benefits of exercise, there is a long-standing concern about potential adverse effects of maternal exercise on the developing fetus. These concerns include placenta hypoxia and fetal bradycardia, low birth weight, premature birth and risk of miscarriage (Bø, Artal, Barakat, Brown, Dooley, et al., 2016). There are, however, poor evidence to support these suspected risks of maternal exercise. Based on study with six elite athletes indicating transient fetal bradycardia when exercising above 90% of maximal heart rate, it is not recommended to perform frequent high intensity exercise (Salvesen, Hem, & Sundgot-Borgen, 2012). The concern for miscarriage seems only to be relevant for strenuous exercise at the time of implantation (Bø, Artal, Barakat, Brown, Dooley, et al., 2016).
Do’s and don’ts
Examples of exercises that are safe during pregnancy are brisk walking, swimming, water aerobics, spinning, yoga, pilates, strength training, jogging or running (the latter for women who have been engaged in these activities on a regular basis before pregnancy) (Haakstad, Dalhaug, & Torstveit, 2018). Some adjustments may be necessary, for instance if running starts feeling uncomfortable as pregnancy progresses, it can be substituted with ellipse training or brisk walking. Training during pregnancy is safe as long as one uses common sense; avoids overheating, energy deficiency, and dehydration, contact sport (e.g. hockey, martial arts, and handball), activities with high risk of falling (e.g. horseback riding, gymnastics, mountain biking, and alpine skiing), hot yoga, scuba diving, and skydiving. Examples of absolute contraindications are shortened cervix, placenta previa after gestation week 26, persistent bleeding and restrictive lung disease (Haakstad et al., 2018).
A little goes a long way
Nausea and fatigue are common afflicts, especially in early pregnancy (Bø, Artal, Barakat, Brown, Davies, et al., 2016), which understandably reduces the motivation for long training sessions. In this regard it is important to remember that the relationship between physical activity and health benefits is dose dependent, i.e. ten minutes are better than none. In normally active women, and even in high-performance elite athletes, training volume seems to decline dramatically during the first trimester, after which it increases in the second trimester with a slight reduction in the third trimester (Nascimento et al., 2015; Solli & Sandbakk, 2018). It is physically demanding to grow a baby, and pregnancy is also a time period where it is particularly important to listen to the body’s signals and take a rest in good conscience when needed (Figure 2). That being said, the positive effects of regular physical activity throughout pregnancy should not be neglected and exercise is a safe and effective way of reducing pregnancy complaints.
Ida Lysdahl Fahrenholtz has a Master of Science in human nutrition from Copenhagen University, Denmark and is currently a PhD student at the Department of Public Health, Sport and Nutrition, University of Agder, Norway. Her main research areas include Relative Energy Deficiency in Sport (RED-S) and the association between exercise and female reproductive function. Personally, she has a great interest in long-distance running and triathlon. E-mail: firstname.lastname@example.org