Pregnancy loss in women with von Willebrand disease: a single-center pilot study.

: The risk of pregnancy loss in von Willebrand disease (VWD) has been inconsistently reported. Von Willebrand factor (VWF) is a known regulator of angiogenesis, so has the potential to affect placental function. We sought to determine the risk of pregnancy loss and placenta-mediated pregnancy complications in women with VWD, compared with women without VWD. Women with VWD followed in the Southern Alberta Rare Blood and Bleeding Disorders Clinic were invited to participate in a questionnaire (February-June 2014). The same questionnaire was sent to women without VWD identified in a low-risk obstetrical clinic in Calgary, Alberta, Canada. The primary outcome was the proportion of pregnancies that ended in pregnancy loss. Secondary outcomes were preeclampsia, fetal growth restriction, placental abruption, and preterm labor less than 37 weeks gestation. Of the 30 (31.6%) VWD participants that responded, 26 (86.7%) were diagnosed with Type 1 VWD, of which 11 (42.3%) had VWF antigen or activity levels less than 30%. In women with VWD, there were 20 pregnancy losses out of 80 pregnancies [25.0%, 95% confidence interval (CI), 16.81-35.48], compared with eight losses out of 50 pregnancies in the control group (16.0%, 95% CI, 8.34-28.51; P = 0.28). There was no difference in the risk of preeclampsia (1.7 versus 0%, P = 1.00) or preterm labor (16.7 versus 7.1%, P = 0.23) among VWD and control groups. There were no other placenta-mediated pregnancy complications reported. There is no significant difference in pregnancy loss between women with and without VWD; however, a large multicenter study is needed to clarify the risk of pregnancy loss in women with VWD.