Physical Activity and the Risk of Preterm Birth: A Systematic Review and Meta-Analysis of Epidemiological Studies

( BJOG 2017;124:1816–1826) Preterm birth, which is associated with neonatal morbidity and many adverse neonatal outcomes, is associated with smoking as well as maternal obesity. The association between physical activity and preterm birth is not clear. A significant inverse relationship has been shown in several randomized trials, cohort studies and case-control studies, while others have shown no significant association. This systematic review...