Antenatal syphilis screening positivity at Port Moresby General Hospital: prevalence, temporal trends, and socio-demographic predictors – a retrospective observational analysis between 2020–2022

Introduction Syphilis, caused by Treponema pallidum, persists as a major public health issue in Papua New Guinea (PNG), contributing to a high rate of congenital syphilis, recently reported as 4276 per 100,000 live births, and adverse pregnancy outcomes. Despite global elimination targets, antenatal screening coverage in PNG remains suboptimal, and recent local data from urban referral settings are limited. This study aimed to determine the prevalence, temporal trends (2020–2022), and socio-demographic predictors of syphilis screening positivity among antenatal mothers at Port Moresby General Hospital (PMGH) using routine registry data. Methods This retrospective registry-based observational study included 4302 antenatal mothers with complete records who were screened using a treponemal Alere Determine™ Syphilis TP rapid diagnostic test (RDT) at PMGH Antenatal Clinic between January 2020 and December 2022. Data on age, parity, marital status, employment, district of residence, settlement residence, and test results were extracted, cleaned, and analysed in SPSS version 22. Prevalence was calculated with 95% confidence intervals (CIs). Trends were assessed via Chi-square linear-by-linear association and logistic regression. Associations were examined using Chi-square tests and multivariable logistic regression (adjusted odds ratios, AORs). Results Overall syphilis screening positivity was 6.4% (95% CI: 5.7–7.2%), declining by 38.5% from 7.8% in 2020 to 4.8% in 2022, with a significant linear trend (linear-by-linear association: χ² = 10.86, P = 0.001). In multivariable analysis, independent predictors of positivity included age 25–29 years (AOR 1.59, 95% CI 1.02–2.50), single/divorced status (AOR 1.43, 95% CI 1.07–1.93), and residence in Moresby North-West (AOR 1.70, 95% CI 1.24–2.33) and Moresby South (AOR 1.42, 95% CI 1.03–1.97). Parity 2 was protective (AOR 0.63, 95% CI 0.43–0.93). Employment and settlement residence showed no association. Conclusion Antenatal syphilis positivity at PMGH remains above global averages but declined markedly over 2020–2022. Identified high-risk subgroups (young adults, unmarried women, specific districts) suggest the need for targeted screening, confirmatory dual testing to address potential yaws cross-reactivity, expanded antenatal care coverage, and integration into maternal health strategies to support PNG’s progress toward congenital syphilis elimination.