title: Effect of Environmental Factors on Low Weight in Non-Premature Births: A Time Series Analysis.
abstract: OBJECTIVE
  Exposure to pollutants during pregnancy has been related to adverse birth outcomes. LBW can give rise to lifelong impairments. Prematurity is the leading cause of LBW, yet few studies have attempted to analyse how environmental factors can influence LBW in infants who are not premature. This study therefore sought to analyse the influence of air pollution, noise levels and temperature on LBW in non-premature births in Madrid during the period 2001-2009.
  
  
  METHODS
  Ecological time-series study to assess the impact of PM2.5, NO2 and O3 concentrations, noise levels, and temperatures on LBW among non-premature infants across the period 2001-2009. Our analysis extended to infants having birth weights of 1,500 g to 2,500 g (VLBW) and less than 1,500 g (ELBW). Environmental variables were lagged until 37 weeks with respect to the date of birth, and cross-correlation functions were used to identify explaining lags. Results were quantified using Poisson regression models.
  
  
  RESULTS
  Across the study period 298,705 births were registered in Madrid, 3,290 of which had LBW; of this latter total, 1,492 were non-premature. PM2.5 was the only pollutant to show an association with the three variables of LBW in non-premature births. This association occurred at around the third month of gestation for LBW and VLBW (LBW: lag 23 and VLBW: lag 25), and at around the eighth month of gestation for ELBW (lag 6). Leqd was linked to LBW at lag zero. The RR of PM2.5 on LBW was 1.01 (1.00 1.03). The RR of Leqd on LBW was 1.09 (0.99 1.19)(p<0.1).
  
  
  CONCLUSIONS
  The results obtained indicate that PM2.5 had influence on LBW. The adoption of measures aimed at reducing the number of vehicles would serve to lower pregnant women's exposure. In the case of noise should be limited the exposure to high levels during the final weeks of pregnancy.
authors: National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
authors: Julio
authors: J
authors: Díaz
authors: Complejo Asistencial Universitario de Salamanca (CAUSA), Salamanca, Spain.
authors: Virginia
authors: V
authors: Arroyo
authors: National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
authors: Cristina
authors: C
authors: Ortiz
authors: National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
authors: Rocío
authors: R
authors: Carmona
authors: National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
authors: Cristina
authors: C
authors: Linares
mesh_terms: D000397:Air Pollution / Q000009:adverse effects; D002947:Cities / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007230:Infant, Low Birth Weight; D019102:Infant, Very Low Birth Weight; D009585:Nitrogen Dioxide / Q000009:adverse effects; D009622:Noise / Q000009:adverse effects; D010126:Ozone / Q000009:adverse effects; D052638:Particulate Matter / Q000009:adverse effects; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology; D012306:Risk; D013030:Spain / Q000453:epidemiology; D013696:Temperature
chemical_list: D052638:Particulate Matter; D010126:Ozone; D009585:Nitrogen Dioxide