Collaborative epidemiological research in perinatology.
D002986:Clinical Trials as Topic; D004463:Ecology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D010500:Perinatology; D011247:Pregnancy; D011446:Prospective Studies; D011897:Random Allocation; D012189:Retrospective Studies