We have demonstrated previously that phenylephrine, a selective postsynaptic alpha-1-adrenergic agonist, significantly potentiates the incidence of acetazolamide-induced right forelimb ectrodactyly in a dose-response manner. As reported herein, phenylephrine also decreases maternal uterine blood flow in a dose-response manner as measured by radioactive microsphere methodology. At the potentiative dose of 12.5 mg/kg phenylephrine decreases uterine blood flow by 86.8% when compared to control. In turn, pretreatment with prazosin, a selective postsynaptic alpha-1-adrenergic antagonist, prevents this large decrease in uterine blood flow and abolishes the potentiation of acetazolamide teratogenesis by phenylephrine. Although the effects of acetazolamide or acetazolamide + phenylephrine on uterine blood flow were not measured the data suggest a correlation between decreased uterine blood flow and potentiation of acetazolamide teratogenesis.