A postpartum nurse is educating a client who is prescribed a medication that requires avoiding pregnancy due to its risk of causing birth defects. Which teaching point should the nurse prioritize to ensure safe use of this medication?

When a medication carries teratogenic risk, the highest priority teaching is ensuring the client uses reliable contraception consistently throughout therapy and for any required washout period afterward. Simply advising consistent use of an alternate birth control method directly addresses the risk of fetal harm and is the cornerstone of teratogen-risk counseling programs such as the iPLEDGE program for isotretinoin or the REMS programs for other teratogens. The withdrawal method is unreliable, with a typical-use failure rate exceeding 20%, making it wholly inappropriate when avoiding pregnancy is medically critical. Instructing the client to stop the medication only after pregnancy occurs fails to prevent the teratogenic exposure entirely, since organogenesis begins within the first weeks of pregnancy, often before it is recognized. Breastfeeding suppresses ovulation inconsistently and is not considered a reliable contraceptive method; it requires exclusive breastfeeding, feeding on demand, and absence of menses, conditions rarely met consistently enough to be protective. Furthermore, many teratogenic medications are also contraindicated during breastfeeding because of infant exposure through breast milk. The nurse must therefore prioritize counseling the client to use a dependable contraceptive method — such as combined oral contraceptives or long-acting reversible contraceptives — both during and after medication therapy for the duration recommended by the prescribing guidelines.