Despite limitations, we observed evidence of a short term effect
at Lag 0 (the same day), for the environmental variables analyzed,
PM2.5 and O3 concentrations and diurnal noise level for the total
number of births, and besides these, heat temperatures at Lag 1
(the preceding day, one day before birth) on preterm births in
Madrid City during the studied period. The public health impact of
air pollutants, noise levels and temperature on reproductive outcomes
may be considerable, due to widespread nature of the exposure
and the possible long-term health effects of preterm birth
(Osmond et al. 2000). Therefore, exists a clear need to explore
causes of preterm delivery that might be modifiable, through the
decrease of air pollution and noise levels and through the behavior
modification of the mothers.