Maternal anti-protein Z antibodies in pregnancies complicated by pre-eclampsia, SGA and fetal death

Objective. Low maternal plasma protein Z PZ concentrations were reported in patients with pre-eclampsia PE, a small for gestational age SGA neonate, and a fetal demise FD. Anti-protein Z antibodies APZ-AB have been proposed as a possible underlying mechanism leading to low plasma PZ concentrations. The objective of this study was to determine the maternal plasma concentration of APZ-AB in women with a normal pregnancy, and patients with PE, an SGA neonate or a FD. Study design. A cross-sectional study included women in the following groups: 1 non-pregnant women n 45; and pregnant women with: 2 normal pregnancies n 70; 3 PE n 123; 4 SGA neonates n 51; and 5 a FD n 51. Plasma concentrations of anti-protein Z IgM and IgG antibodies were measured by ELISA. Elevated APZ-AB was defined as >75th, 90th and 95th percentile of the normal pregnancy group. Non-parametric statistics were used for analyses. Results.1 Patients with an SGA neonate had a higher median maternal plasma IgG APZ-AB concentration than women with normal pregnancies p < 0.001, and patients with PE p < 0.001 or with a FD p 0.001. 2 The proportion of patients with a maternal plasma IgM APZ-AB concentration >90th percentile was higher in the SGA group than in the PE group p 0.01. 3 Patients with PE maternal plasma IgM APZ-AB concentration >90th percentile had a higher rate of villous thrombosis p 0.03 and persistent muscularisation of basal plate arteries p 0.01 than those with IgM APZ-AB concentration <90th percentile; and 5 Patients with FD and maternal plasma IgM APZ-AB concentration >90th percentile had a higher rate of umbilical phlebitis and arteritis than those with IgM APZ-AB concentration <90th percentile p 0.003. Conclusions.1 Patients with SGA neonates have a higher median plasma concentration of IgG APZ-AB than normal pregnant women, or patients with PE or FD; and 2 maternal plasma IgM APZ-AB concentration >90th percentile was associated with vascular placental lesions in patients with PE, but not in those with an SGA neonate, suggesting that in a subset of patients, these antibodies can be associated with abnormal placentation and pregnancy complications.