Burden and distribution of serologically detected HIV and syphilis infections among pregnant women attending antenatal care in peri-urban Blantyre, Malawi.

Pregnant women are vulnerable to sexually transmitted infections (STIs), which can lead to adverse pregnancy outcomes. Evidence on STI prevalence and determinants among pregnant women in peri-urban Malawi remains limited. This study aimed to determine human immunodeficiency virus (HIV) and syphilis prevalence, identify associated factors and assess antenatal care (ANC) service quality among pregnant women in Blantyre peri-urban health facilities. A cross-sectional mixed-methods study was conducted at three peri-urban health centers (Zingwangwa, Ndirande, and Limbe). Quantitative data were retrospectively collected from facility records between January and June 2022 to determine STI diagnoses. Structured questionnaires assessed contributing factors and ANC service quality. Among 5,634 pregnant women tested for HIV, the prevalence of serologically detected HIV was 10.4% (95% confidence interval (CI): 9.7-11.3). Among 2,983 women tested for syphilis, the prevalence was 11.1% (95% CI: 10.0-12.3). The prevalence varied significantly by facility (p < 0.001), with the highest burden recorded at Limbe (HIV: 12.5%, 95% CI: 11.1-13.9; syphilis: 14.8%, 95% CI: 12.8-16.9), versus Ndirande (HIV: 10.5%, 95% CI: 9.1-12.1; syphilis: 8.4%, 95% CI: 6.7-10.3) and Zingwangwa (HIV: 7.5%, 95% CI: 6.2-8.9; syphilis: 8.9%, 95% CI: 7.0-11.0). Among women tested for both infections (n = 2,917), co-infection prevalence was 2.0% (95% CI: 1.6-2.6). Among 91 interviewed women (aged 14-43 years), unemployment (odds ratio (OR) 2.74, 95% CI: 1.07-7.03; p = 0.033) and lack of partner treatment (OR 2.83, 95% CI: 1.12-7.19; p = 0.025) were significantly associated with STI positivity. Although most participants were satisfied with ANC services, 64% reported that their partners were not treated, and no formal follow-up system existed, revealing gaps in partner management. The high HIV and syphilis prevalence highlights a pressing public health concern. Strengthening antenatal screening, improving partner management and implementing targeted interventions are essential to reduce HIV and syphilis burden among pregnant women in peri-urban Blantyre.