Drug effects on fetal physiology as well as possible teratogenesis need to be considered before prescribing for women of child-bearing age. All nonsteroidal anti-inflammatory drugs (NSAIDs), because of their suppression of prostaglandin synthesis, may prolong gestation and labour. Aspirin is also associated with an increased risk of ante- and post-partum haemorrhage. Indomethacin may be teratogenic in humans and like aspirin may induce pulmonary hypertension in the neonate. To reduce the physiological alterations induced by NSAIDs, short-half-life drugs such as ibuprofen, flurbiprofen or ketoprofen should be used at the maximally tolerable dosage interval. Gold salts and corticosteroids show little human evidence of teratogenicity although the largest possible dosage interval of gold should be used. D-Penicillamine may be teratogenic thus it should not be commenced during pregnancy and if a patient becomes pregnant whilst receiving the drug, it should be slowly withdrawn or the dosage reduced. 4-Aminoquinoline compounds are contra-indicated in pregnancy.