Marked variation in antiphospholipid antibodies during pregnancy: relationships to pregnancy outcome

Variations in blood concentrations of antiphospholipid antibodies (APA) wer e investigated through the course of pregnancy in women who had a history o f recurrent pregnancy loss, and were related to changes in pregnancy outcom e. Serial measurements of APA were made in 16 women with antiphospholipid s yndrome (APS) and 16 with negative APA tests pre-pregnancy. There was consi derable intraindividual variation in test results through pregnancy. There was a significantly higher ratio of dilute Russell's viper venom time and I gG ACA titre in the first trimester compared with results pre-pregnancy in women with APS. Furthermore, transiently positive APA results were noted in the control group during pregnancy and some women with antiphospholipid sy ndrome tested negative for APA in mid- and late pregnancy. We have demonstr ated clinically important variations in the results of tests for APA during pregnancy in women with APS.