Without treatment, pregnancies in patients with congenital afibrinogenemia terminate in miscarriage at 5-6 weeks of gestation. Animal model studies have suggested that implantation site bleeding contributes to miscarriage in afibrinogenemia; however, retrochorionic hematoma in human congenital afibrinogenemia has not been previously observed. A patient with congenital afibrinogenemia receiving fibrinogen prophylaxis developed a retrochorionic hematoma in the first trimester. With continuous intensified fibrinogen concentrate replacement the hematoma resolved over 6 weeks, and the patient delivered a healthy infant. Median fibrinogen levels in the first trimester were 48 mg/dL and in second and third trimester 44 mg/dL. Median fibrinogen levels under 60 mg/dL may be adequate to maintain pregnancy in patients with congenital afibrinogenemia, although it is possible that higher levels might reduce the risk of hemorrhagic events.