Box-and-whiskers plot showing the distribution of anti–protein Z IgG and IgM antibody levels in the 5 groups of women. Data are given in arbitrary units (AUs) as described. C indicates control healthy women; P1, patients with at least 3 unexplained primary recurrent embryo losses before the 8th week of gestation; P2, patients with one unexplained episode of fetal death from the 10th week; P3, patients with one episode of severe pre-eclampsia; P4, patients known to be carriers of an association of unexplained primary recurrent embryo losses with a protein Z deficiency. The horizontal line represents the 1-AU level.