Pregnancy, labor and delivery can also be challenging for women with FXI deficiency. In 1999 a study published in the American Journal of Hematology revealed that FXI levels are inconsistent during pregnancy. The incidence of postpartum hemorrhage is increased in women with factor XI deficiency. The incidence is 16% for the primary postpartum hemorrhage in FXI patients, compared with 5% in the general population. Moreover, the incidence is 24% for the secondary postpartum hemorrhage in comparison with that in the general obstetric population (0.7%). The authors recommend that FXI levels be obtained during the initial visit and monitored during the woman's third trimester. For all of these reasons it is important for women who suspect they might have a FXI deficiency to be tested and diagnosed before pregnancy.