Sero-prevalence and Predictors of Syphilis and HIV Co-infection among pregnant women attending ANC in Mekelle City of Conflict-Affected Tigray Region, Ethiopia: Evidence from Firth Penalized Regression

Abstract

Background: Sexually transmitted infections (STIs), particularly syphilis and HIV, significantly impact pregnant women in resource-limited countries, complicating treatment and increasing maternal and neonatal risks. In Mekelle City, Tigray, Ethiopia, barriers including limited antenatal care (ANC) access, physiological vulnerability, behavioral risks, socio-economic constraints, and conflict further exacerbate the burden of these infections, underscoring the critical need for accurate prevalence data and identification of predictive factors. Objective: This study aimed to determine the sero-prevalence of HIV/syphilis co-infection and identify associated predictors among pregnant women attending ANC in Mekelle City. Method: A facility-based cross-sectional study was conducted among pregnant women attending ANC services in selected health facilities across Mekelle City, Tigray, Ethiopia. A two-stage stratified sampling procedure was utilized to draw representative pregnant women under ANC from a health facility in each sub city. Data collection involved an interview-administered questionnaire and pregnant women’s registration books. Due to the relatively small sample size and rarity of co-infection events, Firth penalized logistic regression was employed for statistical analysis to mitigate bias and ensure model stability. Adjusted odds ratios (AOR) with 95% confidence intervals (CI) were computed to identify significant predictors. Result: Out of 438 pregnant women enrolled, the sero-prevalence of HIVsyphilis co-infection was 3.7% (95% CI: 1.87–5.43%). Significant predictors included sexual violence (frequency: 13.7%; AOR=2.2, 95% CI: 1.27–3.81, p=0.001), displacement (frequency: 41.1%; AOR=1.6, 95% CI: 1.10–2.32, p=0.043), frequent alcohol consumption (most frequent: 8.9%; AOR=2.1, 95% CI: 1.27–3.46, p=0.004), and limited ANC visits (frequency: 47.5%; AOR=1.8, 95% CI: 1.13–2.87, p=0.014). Conclusion & Recommendation: The high prevalence of HIV and syphilis co-infection rate underscores the need for targeted sexual violence prevention, improved ANC access, and integrated STI screening within ANC services in Mekelle City. Enhanced education on substance abuse and sexual health is essential.