The Occurrence of Antibodies to Components of the Natural Coagulation Inhibitor System, Protein Z and Protheombin in Normal Pregnancy.

There are recent reports that indicate that antibodies to components of the natural coagulation inhibitor system and coagulation factors, such as FII, are associated with increased risk for thrombosis and adverse pregnancy outcomes (APO) in patients with autoimmune disease and the anticardiolipin syndrome. In view of the importance of the natural inhibitor system in regulating the prothrombotic process and particularly in the hypercoagulable milieu of pregnancy, we studied the occurrence of several of these antibodies in patients characterized with normal pregnancies (NP). We used 82 1st trimester (TRI), 64 2nd TRI, 78 3rd TRI, and 50 non-pregnant controls for this study. Our data are demonstrated in the tables below. The salient features; the PZ and PS IgM antibodies are greater than the non-pregnant controls throughout gestation but the PZ and PS IgG antibodies are greater than non-pregnant controls in the later phases of pregnancy. IgG and IgM antibodies to FII and PC are increased compared to non-pregnant controls throughout gestation. When the antibody levels are compared in NP in each trimester; PZ IgM increases in the 3^rd trimester, PS IgG increase in each trimester and PS IgM in the first two trimesters. FII IgM increases in each trimester and IgG does not increase with gestation. PC IgM increases with each trimester and PC IgG remains unchanged. The prevalence of progressive increases in the antibody response is mainly IgM. This would tend to indicate more acute than chronic response and stimulation. These findings indicate that in NP an immune response is present in most pregnancies that can affect the hemostatic balance. Yet to be determined are the tipping points for pathological consequences.

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