MEDLINE was searched from 1960 to 1991 using the following keywords: 'pregnancy', 'antihistamine', 'antinauseant', 'antiemetic', 'cough/cold', 'morning sickness', 'hyperemesis gravidarum', 'nausea', 'vomiting', 'hypersensitivity', 'allergy', 'adverse fetal outcome', 'malformation', 'congenital abnormalities', 'birth defect', and 'teratogen'.