The high prevalence of migraine in women during their reproductive years means that new drug treatments for migraine, such as the serotonin 5-HT(1B/1D) receptor agonists (the 'triptans'), are likely to be widely used by women of childbearing potential. Scrutiny of these agents in an effort to detect any signal of teratogenicity is thus important. A systematic review of the medical literature was conducted to identify information regarding the safety of sumatriptan during pregnancy. This agent was chosen to be investigated because it has been available for the longest and is the most widely used of the triptan class. Information was obtained regarding the impact of migraine on pregnancy outcome, and data on sumatriptan use in pregnancy were obtained from animal studies, preclinical drug trials, postmarketing surveillance efforts, prospective pregnancy registries, national birth registries and teratogen information services. Synthesis of information from these sources is sufficient to rule out a large increase in birth defects from sumatriptan use during pregnancy and is reassuring for cases where inadvertent exposure to sumatriptan during pregnancy has occurred. However, current information is not sufficient to rule out small increases in the risk for birth defects. For this reason, caution should be exercised in making a positive recommendation for the use of sumatriptan during pregnancy.