Project goal is to evaluate the dose-response relationship between 1-131 thyroid doses (both cumulative and gestation-specific) and a wide range of reproductive endpoints of interest. A secondary goal is to analyze the effects on these endpoints of maternal iodine deficiency/maternal thyroid hypofunction. NCI will provide DESPR with previously collected demographics, medical and dosimeter data on in utero cohorts from contaminated regions of northern Ukraine, to investigate the relationship of prenatal exposure to Iodine-131 and risk of malignancy and benign thyroid disease