Effect of RPR titer of pregnant syphilis on adverse outcome and treatment in 2013-2018, Nanjing, China: a retrospective study

Abstract

Background: We aimed to find the relationship among syphilis Rapid Plasma Reagin (RPR) titer of syphilis infected pregnant women, RPR positive rate of the newborn, the adverse pregnancy outcomes and therapies.Method: A total of 600 syphilis infected pregnant women and their infants were participated in our study. Syphilis RPR Test and Treponema pallidum particle agglutination (TPPA) test screening were performed on mothers and these infants. Mothers were divided into six groups depending on different treatments.Results: The higher the RPR titer of the pregnant mother was, the higher the RPR titer of their newborns after birth. The number of newborns in double negatives (RPR negative and TPPA negative), TPPA positive (RPR negative), RPR < 8 and RPR ≥ 8 groups (P < 0.01) has significantly difference. The infants with TPPA positive and RPR < 1:8 have more possibility to turn double negative than those RPR ≥ 8 infants after 12 months. Among all the adverse events, the number of premature births was significantly higher than others (P < 0.01). The proportion of adverse events achieved highest in RPR ≥ 1:8 group (11.24%), compared with the TPPA positive group (8.41%) and RPR < 1:8 group (2.56%). Therapy efficacy of mothers was better in RPR ≥ 1:8 group than RPR < 8 and TPPA positive groups (P < 0.01).Conclusions: RPR titers of 1:8 could be used as a point of therapeutic induction, which need to be emphasized.