Leisure Time Physical Activity is Associated with a Reduced Risk of Preterm Delivery
Leisure Time Physical Activity is Associated with a Reduced Risk of Preterm Delivery
Abstract & Commentary
By John C. Hobbins, MD
Synopsis: Women in early pregnancy who practice more than 1 type of sports have a significantly reduced adjusted risk of preterm delivery compared with women with no sports activity.
Source: Hegaard HK, et al. Leisure time physical activity is associated with a reduced risk of preterm delivery. Am J Obstet Gynecol. 2008;198:180e1-180e5.
Many pregnant patients ask whether it is bad to exercise regularly and vigorously, while others ask whether exercising in any way helps to improve outcome. These questions were addressed in a recent publication in the American Journal of Obstetrics & Gynecology.
Hegaard et al gathered data from 5,749 patients in Denmark regarding their exercise habits. The questionnaires were completed by the enrolled patients in their second trimester. They were asked to place themselves in one of four categories. For example, if they participated in competitive sports several times a week, they were put into a "heavy activity" group. Those engaging in more than 3 hours of running, swimming, racket sports, or heavy gardening, were designated as "moderate exercises." The "light" category was composed of those walking more than 3 hours a week, doing light gardening, or "similar activity." The last, "sedentary" group was composed of those whose activities consisted mostly of sitting, reading, and watching TV. The primary endpoint was birth before 37 weeks, which occurred in 210 patients in the study.
In culling the data, the authors lumped the moderate and heavy groups together. Two thousand four hundred and forty two (2,442) patients were classified as sedentary, 2,936 as light, and 371 as moderate/ heavy. The rate of preterm birth (PTB) was 4.3%, 3.3%, and1.9%, respectively for each group. Although a 24% reduction in PTB was noted between the sedentary and light activity groups, it was not statistically significant. However, the 90% reduction in PTB between the sedentary and moderate/ heavy group was significant. Those who engaged in active sports had the lowest PTB rate.
It is of note that the authors controlled for confounding variables, such as obesity (no correlation with BMI), and they excluded any patient who had pregnancy complications into the second trimester.
Commentary
This study shows that physical activity, and even engaging in competitive sports into the second trimester, certainly is not detrimental to pregnancy outcome, and may even decrease the chances of PTB. Obviously, a pregnant woman suddenly progressing from a relatively inactive life to a competitive soccer player might not be the best idea, but the bulk of patients who are asking questions about exercise could benefit from the information in the above study.
As pointed out in a previous OB/GYN Clinical Alert, there has been a suggestion that exercising in the second trimester may enhance the process of branching angiogenesis in the placenta. However, excessive exercise in the third trimester may affect adversely the development of terminal villi, and the work of Clapp et al has shown that the ideal regimen would be to continue to exercise well into the second trimester, but to back off somewhat after 24 weeks of gestation.
Additional Reading
- Hegaard HK, et al. Leisure time physical activity is associated with a reduced risk of preterm delivery. Am J Obstet Gynecol. 2008;198:180e1-180e5.
- Clapp JF 3rd, et al. Continuing regular exercise during pregnancy: effect of exercise volume on fetoplacental growth. Am J Obstet Gynecol. 2002;186:142-147
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