False positive results of tests for syphilis and outcome of pregnancy: a retrospective case-control study.

In a retrospective case-control study 64 women yielding a false positive result to a test for syphilis in pregnancy were compared with 128 controls individually matched for age, parity, hospital of delivery, and year of delivery. There were significantly more unsuccessful pregnancies, mainly spontaneous abortions during the first and second trimesters, among women with persistent false positive results. There was no significant difference between groups in the mean birth weights of liveborn infants. The antibodies responsible for the false positive result may indicate the presence of an immunological disturbance. Women who give a false positive result should be carefully managed throughout their pregnancy.