EXPOSURE TO AIR POLLUTION DURING PREGNANCY AND PLACENTAL WEIGTH IN THREE COHORTS IN SPAIN

Background and Aims: Results from epidemiologic studies suggest an association between air pollution exposure and birth size. The aim is to assess the association between exposure to air pollution during pregnancy and placental weight in the Spanish INMA cohorts in Gipuzkoa, Sabadell, and Valencia. Methods: Exposure to traffic air pollution to nitrogen dioxide (NO2) during pregnancy was estimated combining spatial modeling (land use regression) and temporal correction for residence for each trimester and the whole pregnancy for women participating in the INMA cohorts. Study population was 1947 pairs of mothers and their offspring with complete data. Outcomes included were placental weight and placental to fetal weights ratio (PFR). The association between air pollution exposure and birth outcomes was assessed by cohort with linear regression models adjusted for potential confounders. We performed a combined analysis with meta-analysis techniques. Also, we performed sensitivity analysis for the subset of women who spent ?15 hr/day at home during pregnancy. Results: NO2 mean level correspondent to the pregnancy period was 20.1 (sd: 6.4), 31.9 (8.6) and 36.9 (11.1) ?g/m3 to Gipuzkoa, Sabadell and Valencia, respectively. All results by cohort showed no heterogeneity (I2<50%). In the combined analysis, we did not find a significant association between NO2 exposure during pregnancy and either placental weight (?=0.9; 95% CI= -5.8, 7.7) or PFR (% change=0.4; 95% CI= -0.5, 1.13). When the sample was restricted to women who spent ?15 hr/day at home, the results did not change substantially (-1.4; 95% CI= -10.4, 7.6). By trimesters, the results were neither significant. Conclusions: We did not found association between residential NO2 exposure during pregnancy and placental weight. Funded by: Ministry of Science, Spain: ISCIII (G03/176), FIS-FEDER 03/1615, 04/1509, 04/1112, 06/1213, 09/02647 and Fundació Roger Torné