Activated protein C resistance (FV : Q(506)) and pregnancy

Activated protein C (APC) resistance, due to a point mutation in the factor V gene (FV:Q(506)), is a major risk factor for venous thromboembolism. To determine the prevalence of APC resistance in a large series of pregnant wo men, and to elucidate its obstetric consequences, we performed a prospectiv e study in Malmo, Sweden, comprising 2,480 women enrolled in early pregnanc y. The presence of APC resistance (the FV:Q(506) allele) was determined. Th e women were interviewed about their medical histories including venous thr omboembolic events (VTE) in relatives. The outcome variables were the VTE r ate, intrapartum blood loss, and the prevalence of selected pregnancy compl ications such as fetal loss, pre-eclampsia, and intrauterine growth retarda tion. The overall prevalence of APC resistance was 11% (270/2480). The APC-resist ant subgroup did not differ significantly from the non-APC-resistant subgro up in terms of pregnancy complications, but was characterized by an 8-fold higher risk of VTE (3/270 vs. 3/2210), a lower rate of profuse intrapartum haemorrhage (3.7% vs. 7.9%) (p = 0.02), and less intrapartum blood loss (34 0 ml vs. 361 ml) (p = 0.04). Despite the high prevalence of APC resistance in this series of gravidae (1 %), its presence was unrelated to adverse pregnancy outcome apart from an 8 -fold increased risk of VTE.