The pregnancy outcome of laboratory employees in three pharmaceutical in Sweden studied with interviews, postal questionnaires, and register studies. The total material shows only a slightly increased miscarriage rate and normal perinatal mortality and malformation rates. Subdivision into two types of laboratory work, "chemical" and "other," revealed a significant difference, with an increased perinatal death rate and an increased rate of major malformations in the chemical group. This observation supports earlier findings indicating that work during pregnancy in a chemical laboratory can represent a hazard to the fetus.