Trends in immunoglobulin G anticardiolipin antibodies in ten successful heparin-treated pregnancies.

The pregnancies of ten women, all with histories of at least two spontaneous abortions of unknown cause, were followed. All patients were positive for immunoglobulin (Ig) G anticardiolipin antibodies (aCL) and one also for IgM aCL, while none had lupus anticoagulant activity. During pregnancy, the patients were treated with calcium heparin in doses varying between 15,000 and 30,000 IU daily. IgG aCL were assayed on average at the 9th, 17th, 24th and 29th weeks of pregnancy and at the moment of delivery. Mean values of IgG aCL levels during the 10 pregnancies steadily fell as the pregnancies progressed, and this decrease was significant (r = 0.985, P = 0.002). All pregnancies terminated favourably, although delivery was brought forward in eight patients and six of the nine placentas examined showed signs of thrombotic events. We assume that a steady fall in IgG aCL levels during pregnancy may be considered as indicative of a favourable outcome.