In the Negev Region of Israel, population 300,000, with a centralized health care and health data system, we propose to monitor associations of occupational exposure with the following URO (approximate rates in parenthesis): infertility (10%), spontaneous abortion (10%), stillbirth (1%), pregnancy complications (5%), specific birth defects (1%), all birth defects (5%), low birth weight (5%), neonatal morbidity (5%); all URO (25%). Critical covariates include smoking, age, contraceptive use, coexisting disease, parity, spouse exposures, and past reproductivity history. Currently exposed women are estimated to include 150 in hospital operating rooms, 200 laboratory workers, 75 chemical production workers and 20 in mercury thermometer factory; men include 5000 in chemical production, 1000 in agricultural chemical use, 100 in chemical laboratories and 200 in university and hospital laboratories. Adjusting for expected turnover rates, we estimate that overall exposures which have risks of increased URO will include about 5000 men and 1000 women. Since priority in research resources goes to most feasible detection and prevention combinations, we define and examine "minimal detectable risk ratios" based on expected populations sizes and incidences for a two year cohort study with estimated one "exposed pregnancy" per five person years in this young population. We tabulate these risk ratios using a cutoff for false positive at p=0.05 and false negative at p=0.1. Sex ratio changes represent outcomes relatively easily detected. Proposed application of these criteria to Negev populations and an example of such applications to published work place exposures to dioxins are shown.