Advice for pregnant women: Get ready and moving – it is good for you!

12. May 2019.

Today, the global public health discussion is increasingly dominated by slogan “Exercise is Medicine”, which encourages health care providers to include physical activity in their design of treatment plans. On the occasion of this year’s Mother’s day, I would like to illustrate the significance of this perspective for all women about to become mothers, namely by outlining the latest scientific findings regarding the effects of physical activity on pregnancy outcomes.

Traditionally, pregnant women were advised to reduce physical activity levels. This advice was based on concerns that exercise would negatively affect pregnancy outcomes by raising core body temperature, by increasing the risk of maternal musculoskeletal injury due to changes in posture and ligamentous laxity, and by shunting transport of oxygen and nutrients to maternal skeletal muscle rather than to the developing fetus.

Research has provided new information on how pregnant women and their fetuses respond to moderate physical activity, showing no adverse maternal or neonatal outcomes. Moreover, regular moderate physical activity has been shown to result in marked benefits for mother and fetus. Maternal benefits include improved cardiovascular function, limited pregnancy weight gain, decreased musculoskeletal discomfort, reduced incidence of muscle cramps and lower limb edema, mood stability, a reduction of gestational diabetes and gestational hypertension, and less complicated labor. Fetal benefits include decreased fat mass, improved stress tolerance, and advanced neurobehavioral maturation1.

Based on these findings, the American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women, who are free of medical or obstetric complications, follow the American College of Sports Medicine – Centers for Disease Control and Prevention general guidelines for physical activity, and engage in 30 minutes or more of moderate physical activity per day on most, if not all, days of the week.

However, these recommendations are not universally accepted. Some investigators argue that the ACOG guidelines may be too cautious and that there is no firm evidence that exercise at higher intensities produces any harmful effects on the fetus. On the other hand, some authors are reluctant in recommending physical activity during pregnancy, because of the insufficient evidence about benefits and risks.

In order to evaluate the influence of the recommended levels of physical activity on pregnancy, labor and delivery, we conducted an observational study with energy expenditure, aerobic fitness, and sleeping heart rate measured in 44 healthy women in late pregnancy at the University Hospital of Geneva2. The results showed that active women, who engaged in 30 minutes or more of moderate physical activity per day, had better aerobic fitness than inactive women, with no negative effects on fetal condition or outcome of labor and delivery. When controlled for birth weight, maternal weight gain and parity, the risk for operative delivery was lower, and the duration of the second stage of labor was shorter in active when compared to inactive.

Other studies with larger sample sizes further analyzed the beneficial effect of physical activity on the course of labor and delivery. A meta-analyses of 16 randomized controlled trials (3359 women) confirmed that structured exercise significantly reduces risks of cesarean delivery. These findings are important to convince women to be active during pregnancy, and should be recommended by physicians, when this is not contraindicated3.

Unfortunately, physical activity level is generally low in gestation and tends to decrease as pregnancy advances4. The decrease in physical activity during pregnancy is probably attributed to difficulties of movement related to larger body mass and discomfort from pregnancy induced morphological and physiological changes. Reductions also occur as a result of behavior changes with respect to the type of activity and in the pace or intensity at which it is carried out4.

The adoption or continuation of a sedentary lifestyle during pregnancy may contribute to the development of certain disorders such as hypertension, maternal and childhood obesity, gestational diabetes, dyspnea, and preeclampsia. In addition, irregular eating habits and decreased physical activity after delivery influence postpartum weight retention5. Women who retain more body weight after pregnancy have, in general, larger pregnancy body weight gain, higher pre-pregnancy body mass index, marked weight changes in previous pregnancies, lactate slightly less and stop smoking during pregnancy to a larger extent5. In view of the global epidemic of sedentary behavior and obesity-related pathology, physical activity was shown to be useful for the prevention and treatment of these conditions.

Overall, the conclusions drawn from latest scientific research can be said to advocate an active lifestyle for all healthy women with uncomplicated pregnancies. Therefore, dear mothers and mothers-to-be: get ready and moving – it is good for you!

Dr. Katarina Melzer

References:

  1. Melzer K. et al. Physical activity and pregnancy. Cardiovascular adaptations, recommendations and pregnancy outcomes. Sports Med 2010; 40(6):493-507.
  2. Melzer K. et al. Effects or recommended levels of physical activity on pregnancy outcomes. Am J Obstet Gynecol 2010; 202: 226.e1-6.
  3. Domenjoz I. et al. Effect of physical activity during pregnancy on mode of delivery. Am J Obstet Gynecol 2014 Oct; 211(4):401.e1-11.
  4. Melzer K. et al. Pregnancy-related changes in activity energy expenditure and resting metabolic rate in Switzerland. Eur J Clin Nutr.2009; 63(10): 1185-91.
  5. Melzer K, Schutz Y. Pre-pregnancy and pregnancy predictors of obesity. Int J Obes (Lond) 2010; 34 Suppl. 2:S44-52.