Table 5

Associations between air pollutants and preterm births by season of conception#, Sydney, 1998–2000

Autumn n = 31 008
 Winter n = 31 097
 Spring n = 31 563
 Summer n = 30 446


OR‡
 95% CI
 OR
 95% CI
 OR
 95% CI
 OR
 95% CI
PM10 24-hour average
 1.462**
 1.267–1.688
 1.343**
 1.190–1.516
 1.119
 0.973–1.288
 0.913**
 0.889–0.937
PM2.5 24-hour average
 1.080
 0.912–1.281
 1.426**
 1.264–1.608
 1.156
 0.972–1.375
 0.879**
 0.839–0.922
O3 1-hour maximum
 1.012
 0.987–1.037
 0.989
 0.972–1.007
 1.093**
 1.019–1.071
 1.031**
 1.023–1.040
NO21 hour maximum
 1.045
 0.963–1.134
 1.153**
 1.066–1.247
 1.002
 0.933–1.077
 0.957**
 0.938–0.976
CO 8 hour maximum
 0.114**
 0.086–0.152
 0.134**
 0.062–0.281
 0.584
 0.283–1.462
 0.633**
 0.535–0.750
SO2 1-hour maximum
 6.489**
 4.365–9.648
 1.323**
 1.027–1.704
 1.287
 0.955–1.734
 0.826**
 0.759–0.898

#Analysis for the first trimester of pregnancy; ‡OR estimates adjusted for: maternal age, maternal smoking during pregnancy, indigenous status, SES, gestational age at first antenatal visit and parity. OR is for a one unit increase in air pollutant concentration; *p < 0.05; **p < 0.01

Jalaludin et al. Environmental Health 2007 6:16   doi:10.1186/1476-069X-6-16