Factor VIII levels and bleeding according to factor 8 (F8) mutation in pregnant carriers of haemophilia A: a multicentre retrospective cohort study

Summary This retrospective cohort study investigated the association between factor 8 (F8) genotype severity and factor VIII (FVIII) levels during pregnancy for 52 women (64 pregnancies) who were heterozygous carriers of mild, moderate or severe haemophilia A. There were no significant differences in FVIII levels for carriers of mild, moderate or severe haemophilia A at baseline [mean (SD) level: mild, 0·78 (0·22); moderate, 0·83 (0·33); severe, 0·70 (0·25) iu/ml; P = 0·81] or in the third trimester [mean (SD) level: mild, 1·42 (0·28); moderate, 1·47 (0·41); severe, 1·37 (0·49) iu/ml; P = 0·80). Post‐partum haemorrhage rates were higher for carriers of severe haemophilia A (13/24; 54·2%) compared to carriers of mild haemophilia A (four of 14; 28·6%).