Abstract
Our study was based on residence within the boundaries of the former Northern health region in the north east of England, with a population of 3 million and about 35 000 deliveries per year. Artificially fluoridated and non-fluoridated areas were chosen with similar populations, sociodemographic characteristics, termination rates, and fluoride supplement regimens. Cases were identified from two population based registers, the Northern Perinatal Mortality Survey (PMS) and the Northern Congenital Abnormality Survey (NorCAS).3