Objective: To investigate the relationship between leisure time physical activity (LTPA) during pregnancy and preterm birth.
Methods: A cross-sectional, population-based study evaluated LTPA during pregnancy in 4147 mothers using data from the 2004 Pelotas Birth Cohort Study. Gestational age was determined by last menstrual period, or when not available, by ultrasound or the Dubowitz method. Type of LTPA, length of usual session, and frequency were determined for each trimester.
Results: A total of 14.6% of all births were considered preterm. Only 13.3% of women reported engaging in LTPA during pregnancy. After adjusting for confounders, LTPA in all 3 trimesters (prevalence ratio [PR] 0.55; 95% confidence interval [CI] 0.32-0.96), LTPA in the third trimester (PR 0.50; 95% CI 0.31-0.80), and minimum LTPA (> or = 90 min/week) in the third trimester (PR 0.58; 95% CI 0.34-0.98) showed a protective association with preterm birth in the adjusted analysis.
Conclusion: LTPA, especially throughout pregnancy and in the third trimester, was associated with a lower chance of preterm birth.