Driving down lengths

Exposure to particles of pollution below the particle size 10 micron (PM10) in the US has increased the incidence of preterm birth -- birth before the 37th week of pregnancy -- from 7.9 per cent to 10.2 per cent over the last 20 years. A study involving 97,518 newborns in South California showed that maternal exposure to PM10 during the first month of pregnancy had increased the chance of having a preterm baby by 16 per cent and recorded a 20 per cent increased chance where exposure had occured during the six weeks before birth (Epidemiology , Vol 11, No 5).