AbstractFrom 1964 to 1976, a cohort study was performed in West Germany to study the possible influence of various factors on pregnancy and child development. Results of the evaluation of 13,643 pregnancies are given with respect to possible teratogenetic effects of antiemetic drugs and sex hormones administered in early pregnancy. There was no evidence of an increased risk of major malformations following the intake of certain antiemetic drugs and progesterone. Also, the use of a hormonal pregnancy test was not significantly associated with an increase of major malformations.