Antiseizure medications and oral contraceptives: Impact of enzyme inducers on pregnancy outcomes and costs

•Enzyme inducing antiseizure medications reduce oral contraceptive efficacy.•This drug–drug interaction may cause >500 unintended pregnancies annually in the US.•Unintended pregnancies may harm the health of women with epilepsy and their infants.•This drug interaction may increase annual pregnancy healthcare costs by $3 million.•Readers can use the online Excel model to calculate these outcomes for other regions.