CO-77 | PERINATAL MANAGEMENT IN WOMAN WITH MILD HEMOPHILIA B: A TWIN PREGNANCY CASE

T. Martini¹, B. Borsellino^1|2, B. Pollio¹ | ¹Haemophilia Centre, Immune-Haematology and Transfusion Medicine, University Hospital “Città della Salute e della Scienza”, Torino, Italy; ²Department of Biomedicine and Prevention, PhD in Immunology, Molecular Medicine and Applied Biotechnology, University of Rome Tor Vergata, Roma, Italy

Background. Women affected by hemophilia and hemophilia carriers may face bleeding challenges during pregnancy and delivery, particularly for hemophilia B (HB), given that factor IX levels do not increase in pregnancy. Evidence on the use of extended half-life (EHL) factor IX concentrates in this setting remains very limited.
Case Report. This case describes the perinatal management of a 29-year-old woman with mild hemophilia B (c.707G>A p.Gly236Asp factor IX gene variant; baseline factor IX 37%; International Society of Thrombosis and Haemostasis Bleeding Assessment Tool): 0) carrying a monochorionic biamniotic twin male pregnancy. Family history included severe HB in the maternal uncle, cousins, and great-uncle; the maternal grandmother and great-aunt were HB carriers. The pregnancy course was regular. Maternal factor IX levels remained stable: 15 weeks GA (gestational age) 41%, 32 weeks GA 49%. Genetic counseling was offered; invasive prenatal diagnosis declined. An elective caesarean section was performed at 35 weeks GA for obstetric indication. Preoperative Eftrenonacog Alfa (Alprolix®) 3000 IU (33 IU/kg) infused 30 minutes prior, achieving post-infusion factor IX 55%; tranexamic acid 10 mg/kg IV 1 h pre-procedure then every 8 hours; strict no-forceps/vacuum policy. Estimated blood loss: 500 ml. Atraumatic cord blood sampling showed neonatal factor IX levels of 37%. The postpartum course was unremarkable: normal lochia and wound healing, maternal factors IX 43% at 24 hours; LMWH (Low Molecular Weight Heparin) 4000 IU/day thromboprophylaxis was started at day 1 to day 8; the patient was discharged at day 4 without bleeding. No primary/secondary postpartum hemorrhage occurred; no additional factor IX infusions were required: a single EHL factor IX infusion provided effective haemostatic coverage for caesarean delivery with minimal blood loss and excellent peripartum safety. A multidisciplinary team (hematologist, obstetrician, anesthesiologist, neonatologist, and coagulation laboratory physician) defined antenatal strategy minimizing maternal bleeding risk and neonatal trauma through coordinated replacement therapy timing, antifibrinolytics, obstetric planning, and postpartum surveillance.
Conclusions. Published experience on EHL factor IX use in pregnant HB women remains scarce, particularly twin gestations where maternal-foetal management complexity increases. Our case outcome supports individualized Eftrenonacog Alfa prophylaxis as an effective option for delivery management in mild HB women, making feasible a tailored peripartum care that balances maternal hemostasis, neonatal assessment, and thromboprophylaxis needs in high-risk coagulation disorders.