Peripartum management of a monochorionic diamniotic twin pregnancy in a woman with mild hemophilia B using eftrenonacog alfa: a case report: A safe delivery in a high-risk setting

Pregnancy and delivery in women with hemophilia B remain clinically challenging, particularly because factor IX levels do not rise physiologically during gestation and published experience with extended half-life factor IX concentrates in this setting is still limited. We report the perinatal management of a 29-year-old woman with mild hemophilia B carrying a monochorionic biamniotic twin male pregnancy. Maternal factor IX levels remained stable throughout pregnancy, while serial ultrasound assessments showed normal growth parameters in both twins. Elective cesarean section at 35 weeks was managed with a single preoperative infusion of eftrenonacog alfa 3,000 IU and tranexamic acid, resulting in effective hemostatic coverage, resulting in minimal blood loss, and uncomplicated maternal and neonatal outcomes. This case highlights the value of individualized multidisciplinary care and supports the feasibility of extended half-life factor IX prophylaxis in complex obstetric settings.