by Woods M

Prenatal care can increase health benefits for both mother and baby as well as reduce the risk of certain complications. It not only includes seeking medical care but also adopting certain lifestyle habits. Good nutrition and regular physical activity have both been linked to a number of benefits including a healthy birthweight for babies.

Researchers from Canada wanted to estimate the influence of structured prenatal exercise on birth weight. A secondary assessment was done on the rate of cesarean since one reason for cesarean is a larger than normal fetus. The study, published in The Cochrane Database of Systematic Reviews, found that that structured prenatal exercise reduces the risk of having a large newborn without increasing the risk of low birth weight babies. Exercise was also associated with a lower risk of cesarean section.

About the Study

The meta-analysis included 28 randomized trials evaluating exercise interventions in 5,322 pregnancies for which birth size information was available. Participants were assigned to a standard prenatal care group or a standard prenatal care group plus supervised prenatal exercise group of at least 1 exercise session every 2 weeks throughout the study duration.

Participants who were in the prenatal exercise group were:

  • 31% less likely to have a large newborn (birth weight of 8.8 pounds)
  • 20% less likely to need cesarean section
  • no more likely to have a low birth weight baby than those without exercise program

The mothers that participated in the regular exercise program also gained less weight than those in the group that did not receive the exercise intervention.

How Does this Affect You?

A systematic review is considered a highly reliable form of research because it includes a large number of participants. However, the review is only as reliable as the studies that make it up. This systematic review contained randomized trials, which is generally a reliable form of research; however, most of the included trials were low to moderate quality. The low quality can decrease the reliability of the outcomes.

This study supports previous trials that have found that exercise during pregnancy may provide benefits like healthy weight for mom and baby. This study also did not find a link between exercise and harmful outcomes like low birth weight. Which exercise program is chosen will depend on the individual. If a mother was active before pregnancy, most can continue their program through pregnancy with minor modifications. Starting a regular routine during pregnancy can also be effective but should be done in consultation with the doctor. As with any pregnancy, working with a pregnancy professional is important. Work with your team to talk about challenges for your physical activity program.


American Congress of Obstetrics and Gynecology 

Family Doctor—American Academy of Family Physicians 


Cesarean delivery. EBSCO DynaMed website. Available at: Updated June 18, 2015. Accessed June 26, 2015.

Wiebe HW, Boulé NG, et al. The effect of supervised prenatal exercise on fetal growth: a meta-analysis. Obstet Gynecol. 2015 May;125(5):1185-1194.

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