There has been a dramatic worldwide increase in the prevalence of obesity or overweight and physical inactivity in women of reproductive age. Growing evidence suggests that pre-pregnancy maternal abnormal body mass index (BMI) and lower physical activity level are associated with poor maternal health and perinatal outcomes. The aim of this study was to assess how self-perceived exercise and pre-pregnancy BMI are associated with preterm birth, low birth weight, and type of birth. We conducted a retrospective cross-sectional study of 394 Polish women in the postpartum period. We used a questionnaire with the structure of the medical interview. To analyze factors related to birth outcomes, we used the Pearson's Chi-squared test of independence and odds ratio (OR), with a corresponding 95% confidence interval (CI), followed by a multiple logistic regression. Women who reported being physically active before pregnancy (p = 0.00) and during pregnancy (p = 0.03) were more likely to give birth on time and had a lower incidence of very-premature and extremely premature births compared to inactive women. Importantly, they were more likely to have vaginal birth (p = 0.03). Pre-pregnancy BMI influenced the week of delivery, i.e., inadequate, too-high BMI contributed to an increase in the percentage of premature births [OR (95% CI) = 1.19 (1.06; 1.34)]. The findings indicate that promoting physical activity and weight management remains a priority in public health policy, and women of childbearing age should be encouraged to adopt or maintain an active and healthy lifestyle during pregnancy in order to avoid sedentary- and obesity-associated risks affecting birth and newborns' health.
Keywords: birth outcomes; exercise; pre-pregnancy BMI; preterm birth.