Evidence-based assessment of pregnancy outcome after sumatriptan exposure.

OBJECTIVE: Assessment of best available evidence for tolerability of sumatriptan after inadvertent exposure during pregnancy.
BACKGROUND: Migraine's demography suggests that inadvertent exposure to acute therapies is likely during the earliest undiagnosed stages of pregnancy. The tolerability of such therapies under these conditions is not amenable to clinical trial for ethical reasons. In the United States, sumatriptan is currently labeled pregnancy category C (ie, not recommended for use during pregnancy unless the potential benefit justifies the potential risk to the fetus).
METHODS: Three types of adverse events were studied: spontaneous abortion, fetal abnormality, and obstetric complications. Traditional evidence-based criteria were used to assess a search-protocol product of four clinical studies and two case reports.
RESULTS: The single positive finding ("preterm delivery" without low birth weight) was in the smallest study; this study was retrospective and the finding was externally inconsistent with the other three larger studies, all of which were prospective. No study followed children for more than 4 years, which is the period needed to identify the maximum number of congenital anomalies. Rigorous teratological technique was generally not employed. Post hoc power calculations were used to provide parameters of the hazard detectable by these studies in aggregate.
CONCLUSIONS: Pregnancy categories B and C both seem feasible for sumatriptan. Within the limits of the examined studies, there is no evidence for any specific effect of sumatriptan on pregnancy outcome. Patients inadvertently exposed to sumatriptan during an early stage of pregnancy should be reassured by these data.