[Effects of high temperature and air pollution on the risk of preterm births. Analysis in six Italian cities, 2001-2010]. / Effetti delle alte temperature e dell'inquinamento atmosferico sul rischio di nascita pretermine. Analisi in sei città italiane, 2001-2010.

ABSTRACT

OBJECTIVES: to evaluate the association between short term maternal exposure to high temperature and air pollution on preterm births (PBs), which represent the first cause of perinatal mortality and morbidity in developed Countries, and to identify maternal risk factors enhancing individual susceptibility. DESIGN: time series. SETTING E PARTICIPANTS: all singleton live-births occurred in six Italian cities between 1st April and 31st October of each year in the period 2001-2010 were identified through the Certificate of Delivery Care Registry (CedAP). MAIN OUTCOME MEASURES: births occurred between 22nd and 36th week of gestation were defined as preterm births. Daily values were obtained for maximum apparent temperature (MAT), PM10, NO2, and O3. Exposures-preterm births association was estimated using a generalized additive model (GAM) with a Poisson distribution. Exposure and city-specific lag structure were computed using a non-linear distributed lag model (DLNM). RESULTS: 121,797 newborns were enrolled, 6,135 (5.0%) of which were PBs. For MAT, a linear relationship was observed for Turin (Piedmont Region, Northern Italy), Trieste (Friuli Venezia Giulia Region, Northern Italy), Rome (Lazio Region, Central Italy), and Palermo (Sicily Region, Southern Italy), while non-linear relationship was found for Bologna (Emilia-Romagna Region, Northern Italy) and Venice (Veneto Region, Northern Italy). The relative risks (RR) for MAT, computed comparing the 90th vs. the 75th percentile, vary from 1.02 (95%CI 0.95-1.09; lag 0-2) in Palermo to 1.94 (95%CI 1.32-2.85; lag 0-3) in Venice. For pollutants, a significant effect for 10 µg/m3 (IQR) increase of PM10 in Rome (RR 1.07; 95%CI 1.02-1.12; lag 12-22) and for 16 µg/m3 (IQR) increase of O3 in Palermo (RR 1.29; 95%CI 1.03-1.62; lag 2-9) was detected. In Rome, a significant effect modification by age and education level of the MAT-PB relationship and by education level and clinical conditions of PM10-PB was found. CONCLUSIONS: results showed a clear positive association between MAT and the risk of NP and a lower and variable effect of pollutants. It is important and necessary to limit the impact of these risk factors on the probability of NP with appropriate prevention programmes.