Background: Women with hereditary fibrinogen disorders (HFDs) seem to be at increased risk of adverse obstetrical outcomes, but epidemiologic data are limited Patients/methods: We conducted a retrospective and prospective international study to determine the prevalence of pregnancy complications, the modalities and management of delivery, and the postpartum events.

Objectives: We aimed to determine the prevalence of pregnancy complications; the modalities and management of delivery; and the postpartum events in women with hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia.

Methods: We conducted a retrospective and prospective multicentric international study.

Results: A total of 425 pregnancies were investigated from 159 women (49 hypofibrinogenemia, 95 dysfibrinogenemia, 15 hypodysfibrinogenemia). Overall, only 55 (12.9%) pregnancies resulted in an early miscarriage, 3 (0.7%) in a late miscarriage and 4 (0.9%) in an intrauterine fetal death. Prevalence of live birth was similar among the types of HFD (p=0.31). Obstetrical complications were observed in 54 (17.3%) of live birth pregnancies, including vaginal bleeding (14, 4.4%), retroplacental hematoma (13, 4.1%), and thrombosis (4, 1.3%). Most 56deliveries were spontaneous (218, 74.1%) with a vaginal non-instrumental delivery (195, 63.3%). A neuraxial anesthesia was performed in 116 (40.4%) pregnancies, while 71 (16.6%) and 129 (44.9%) were under general or no anesthesia, respectively. A fibrinogen infusion was administered in 28 (8.9%) deliveries. Postpartum hemorrhages were observed in 62 (19.9%) of pregnancies. Postpartum venous thrombotic events occurred in 5 (1.6%) pregnancies. Women with hypofibrinogenemia were more at risk of bleeding during the pregnancy (p=0.04).

Conclusions: Compared to European epidemiologic data, we did not observe a greater frequency of miscarriage while retroplacental hematoma, postpartum hemorrhage and thrombosis were more frequent. Delivery was often performed without locoregional anesthesia. Our findings highlight the urgent need for guidance on management of pregnancy in HFDs.