Racial and ethnic differences in congenital syphilis: mathematical modeling study analyzing the role of prenatal care

BackgroundSyphilis screening and treatment coverage remain lower than recommended among pregnant women in the US. ObjectiveWe estimated the prevalence and incidence of syphilis among pregnant women, incidence of congenital syphilis and the impact of improved prenatal care cascade by race and ethnicity. DesignCompartmental mathematical model of syphilis natural history, prenatal care, and syphilis screening and testing SettingUnited States ParticipantsPregnant women MeasurementsWomen were stratified by race and ethnicity and whether they received any prenatal care. The model was calibrated to epidemiological data for 2019. InterventionsWe evaluated improvements among women with any prenatal care and in all pregnant women, and we examined 100% treatment completion, first-trimester testing, first-trimester testing with 100% treatment, testing twice and testing twice with 100% treatment. ResultsWe estimated that, per 100,000 pregnant women, 110 (95% uncertainty interval [UI] 110-120) had syphilis at pregnancy onset, 13 (95% UI 10-15) acquired syphilis during pregnancy, and 13 (95% UI 12-14) had a syphilis-attributable stillbirth (95% UI 12-14). We estimated a 61% (95% UI 60-62) reduction in non-stillbirth-related congenital syphilis outcomes when at least two syphilis tests were provided and treatment was completed among women who receive prenatal care, and a 98% (95%UI 98- 99%) reduction if two tests were provided and treatment was completed for all pregnant women. The largest benefit of expanding testing and treatment to all pregnant women was seen in non-Hispanic Black and Hispanic populations. LimitationsResults represent national averages and do not account regional variation. ConclusionReaching women without prenatal care would substantially reduce congenital syphilis and racial and ethnic differences in congenital syphilis burden. Primary Funding sourceCenters for Disease Control and Prevention.