To the Editor: In Sweden many pregnant women work in hospitals and may thereby be exposed to unspecified teratogens. We studied the outcome of pregnancy among such women (doctors, nurses, laboratory assistants, junior nurses and nurse assistants). We evaluated delivery data on all women employed in hospital work in Sweden during the period 1973–1975 and compared them with delivery records of all births in Sweden during the same interval. The data on women employed in hospitals were updated once a year. From this group we drew a 1 per cent sample; we determined that the actual occupation during the pregnancy . . .