Every child with severe or moderate haemophilia A or B, born in Sweden during the period 1970-1990, was treated in the national haemophilia register, all 117 case records being surveyed for mode of delivery and perinatal complications. Of the 117 deliveries, 13 were by caesarean section and the remaining 104 vaginal. Of the 13 caesarean sections, 2 were performed because the woman was a haemophilia carrier, the remaining 11 (5 emergency, 6 elective) for other reasons. Neonatal complications were: subgaleal or cephalic haematoma (n = 12), intracranial haemorrhage (n = 4), umbilical bleeding (n = 4), haematuria (n = 1), retro-orbital bleeding (n = 1) and abnormal bleeding after surgery, injection or venepuncture (n = 28). Of the 12 infants with subgaleal/cephalic haematoma, 10 were delivered by vacuum extraction. Seven more infants were delivered by vacuum extraction and another 11 were born without abnormal bleedings after laborious (> 24 h) delivery. Of the 4 children with intracranial haemorrhage, all were sporadic cases of haemophilia, 1 was a premature birth by caesarean section in the 27th week, I was delivered by vacuum extraction and the remaining 2 vaginally. In these 4 cases there were no sequelae or only minor ones. We conclude that the risk of serious bleeding in conjunction with normal vaginal delivery is small, but that vacuum extraction should be avoided when delivering offspring of haemophilia carriers.