Maternal titers after adequate syphilotherapy during pregnancy

Background. We aimed to construct a timeline for nontreponemal titer decline specific to pregnancy and evaluate factors associated with inadequate decline by delivery. Methods. This was a retrospective medical records review from September 1984 to June 2011 of women diagnosed with syphilis after 18 weeks of gestation. Women were treated according to stage of syphilis per Centers for Disease Control and Prevention guidelines. Patients with both pretreatment and delivery titers were included for data analysis. Demographics, stage of syphilis, maternal titers, delivery, and infant outcomes were recorded. Standard statistical analyses were performed for categorical and continuous data. The titer decline was analyzed using mixed-effects regression modeling. Results. A total of 166 patients met inclusion criteria. Mean gestational age at treatment was 29.1 ± 5 weeks, and 93 (56%) women were diagnosed with early-stage syphilis. For all stages of syphilis, maternal titers declined after syphilotherapy. Pretreatment titers were higher and declined more rapidly in primary and secondary disease than in latent-stage disease and syphilis of unknown duration. Sixty-three (38%) patients achieved a 4-fold decline by delivery. Patients without a 4-fold decline by delivery were older (24.6 vs 21.5 years; P < .001), treated later in pregnancy (30.3 vs 27.3 weeks; P < .001), diagnosed with latent syphilis or syphilis of unknown duration, and had less time from treatment to delivery (7.8 vs 11.1 weeks; P < .001). Conclusions. Maternal serologic response during pregnancy after adequate syphilotherapy varied by stage of disease. Failure to achieve a 4-fold decline in titers by delivery is more a reflection of treatment timing than of treatment failure.