Objectives There is growing evidence for an adverse effect of maternal exposure to air pollution on pregnancy outcomes. As European data on this topic are limited, the aim of this study was to evaluate the impact of maternal exposure to traffic-related air pollution during different periods of pregnancy on preterm birth and fetal growth.

Methods We estimated maternal residential exposure to NO₂ during pregnancy (entire pregnancy and trimesters) for 7600 singleton births participating in the Amsterdam Born Children and their Development (ABCD) prospective birth cohort study by means of a temporally adjusted land-use regression model. Associations between air pollution concentrations and preterm birth and fetal growth (expressed as small for gestational age and term birth weight) were analysed by means of logistic and linear regression models with and without adjustment for maternal physiological, lifestyle and sociodemographic characteristics.

Results There was no indication of an increase in preterm birth among highly exposed women. Children of mothers with NO₂ levels in the highest exposure category on average had the highest term birth weight of all children and were among those with the lowest risk of being small for gestational age with little indication of a dose–response relationship.

Conclusions In this study, there is no evidence for a harmful effect of estimated maternal exposure to traffic-related air pollution during pregnancy on pregnancy outcomes such as preterm birth, small for gestational age and term birth weight.