Leisure Time Physical Activity (LTPA) during the Last Three Months of Pregnancy and Pregnancy Outcomes. A Case-Control Study in Italy

INTRODUCTION: Studies about the influence of leisure time physical activity (LTPA) during the last three months of pregnancy on pregnancy outcomes are scarce. The aim of this study was to explore the association between LTPA and preterm birth and low birth weight. METHODS: A population-based case-control study was performed in nine Italian cities. Preterm births were singleton births occurring before a gestational age of 37 complete weeks, while low birth weight (LBW) cases were newborns with weight less than 2500 g. Controls were babies with gestational ages > 37th completed week of pregnancy and a birth weight over 2500 g. A total of 299 preterm births, 364 LBW cases and 855 controls were enrolled in the study. A self-administered questionnaire was used to assess socio-demographic variables, medical and reproductive history, life-style habits and LTPA, referred to the last three months of pregnancy. Univariate and multivariate regression analyses were performed in order to estimate odds ratios and 95% CI. RESULTS: LTPA during the last three months of pregnancy seems to be protective against preterm delivery (adjusted OR= 0.56; 95% CI 0.39-0.79). The frequency of LTPA, expressed as times/week, doesn’t show a dose-response relationship. Among the different types of physical activity, only walking activity, the most frequently referred activity, appears significantly protective on preterm delivery (adjusted OR= 0.53; 95% CI 0.36-0.81). Swimming, physical training, go biking do not evidence a protective effect after controlling for confounding variables. LTPA was not found significantly associated with LBW, even if walking activity shows a light protective effect (adjusted OR= 0.72; 95% CI 0.51-1.00). CONCLUSIONS. LTPA and in particular walking activities during the last three months before delivery was associated with a significantly reduced risk of preterm delivery. Walking was found to be lightly protective on LBW.