Addresses were geocoded according to the mother's residence at the time of delivery, matched to the street center points (135,311births) or neighborhood centeroids (216births) using a geocoding algorithm (ESRI, Redlands, CA, USA) (research area see Fig. 1). Street center points were calculated at the middle of the running length of the street (Agay-Shayetal.,2011). Exposure estimates were calculated forweek3–8 of pregnancy, because this period is considered to be the critical exposure window for cardiac system development (Vrijheid et al., 2010).The date of conception was calculated based on the date of birth and gestational age.