tailieunhanh - Air pollution exposure during pregnancy and reduced birth size: a prospective birth cohort study in Valencia, Spain

A procedure was designed to assess individual exposure to NO2 as a marker of outdoor air pollution considering both spatial and temporal variations on exposure. Ambi- ent NO2 concentrations for 93 sampling points covering the study area were obtained using radial symmetry pas- sive samplers (Radiello®, Fondazione Salvatore Maugeri, Padua/Italy) which remained exposed for four sampling periods of 7 days each. The campaigns took place in April, June, and November 2004 and February 2005. The passive samplers were distributed over the area according to geometrical criteria, taking into account the expected pollution gradients and the expected num- ber of births (Figure 1). For obtaining estimates of the NO2 spatial distribution in the study. | Ballester et al. Environmental Health 2010 9 6 http content 9 1 6 ENVIRONMENTAL HEALTH RESEARCH Open Access Air pollution exposure during pregnancy and reduced birth size a prospective birth cohort study in Valencia Spain Ferran Ballester1 2 3 Marisa Estarlich2 1 Carmen Iniguez1 2 Sabrina Llop2 1 Rosa Ramón2 4 Ana Esplugues1 2 Marina Lacasana5 2 Marisa Rebagliato6 2 Abstract Background Maternal exposure to air pollution has been related to fetal growth in a number of recent scientific studies. The objective of this study was to assess the association between exposure to air pollution during pregnancy and anthropometric measures at birth in a cohort in Valencia Spain. Methods Seven hundred and eighty-five pregnant women and their singleton newborns participated in the study. Exposure to ambient nitrogen dioxide NO2 was estimated by means of land use regression. NO2 spatial estimations were adjusted to correspond to relevant pregnancy periods whole pregnancy and trimesters for each woman. Outcome variables were birth weight length and head circumference HC along with being small for gestational age SGA . The association between exposure to residential outdoor NO2 and outcomes was assessed controlling for potential confounders and examining the shape of the relationship using generalized additive models GAM . Results For continuous anthropometric measures GAM indicated a change in slope at NO2 concentrations of around 40 pg m3. NO2 exposure 40 pg m3 during the first trimester was associated with a change in birth length cm 95 CI to and with a change in birth weight grams to the same exposure throughout the whole pregnancy was associated with a change in birth HC of cm to . The shape of the relation was seen to be roughly linear for the risk of being SGA. A 10 pg m3 increase in NO2 during the second trimester was associated with being SGA-weight odds ratio OR . For SGA-length the