A meta-analysis noted a decrease of 2 g (95% CI: 7 to 3) and 2 g (95% CI: 8 to 4) and in birth weight for a 10 mg/m³ increase in PM10 and NO2 concentration.
In contrast to these studies in term born singletons, in ourstudy air pollution was not associated with birth weight nor with small for gestational age, in term born twins.