Lay summary
This research will investigate the association between nitrate in drinking water and congenital anomalies. It will conduct a retrospective cohort study using a national cohort of births from 2009-2021 (~700,000) to assess the impact of prenatal exposure to nitrate in drinking water on congenital anomalies. The cohort will be identified using the Integrated Data Infrastructure (IDI) which will provide individual-level data on key confounders. Nitrate exposure via drinking water will be assessed through collation of testing results and spatial data on water supply boundaries from registered water supplies. The project has a specific focus on water sources in the Ngāi Tahu Takiwā and includes primarily testing of key drinking water sites (e.g. Ngāi Tahu marae).