Reactivity against phospholipids during pregnancy.

Antibodies against phospholipids (PLa) are often thought to be associated with the development of activated protein C (APC) resistance. In the present study, PLa were followed throughout 29 healthy pregnancies and compared to APC resistance. The level of PLa did not change during pregnancy [6.9 +/- 3.7 GPL week 12 versus 6.3 +/- 2.8 GPL week 37; 3.3 +/- 1.8 MPL versus 3.2 +/- 1.5 MPL; and lupus anticoagulant (LA) coefficient 0.99 +/- 0.11 versus 0.94 +/- 0.09], in contrast to the APC resistance, which was suppressed (0.96 +/- 0.22 versus 0.78 +/- 0.13, P < 0.05), but both parameters elevated after delivery (up to 8.7 +/- 4.2 GPL; 1.13 +/- 0.1 LA coefficient; 1.11 +/- 0.22 nAPC ratio; P < 0.05). Three women possessed PLa (1 CLa IgG +/- IgM; 1 IgG CLa +/- PSa +/- PEa; 1 PSa), no LA activity was registered. In the PLa-positive women, dynamics of the nAPC ratio during pregnancy was not related to PLa.