Impact of standardized penicillin therapy on pregnancy outcomes in maternal syphilis: a retrospective cohort study (2013–2023)

Abstract

Introduction: The aim of this study was to assess the impact of standardized benzathine penicillin therapy on adverse pregnancy outcomes in high-titer toluidine red unheated serum test (TRUST) positive (≥ 1:16) syphilis cases and refine prevention of mother-to-child transmission (PMTCT) strategies.

Methodology: This retrospective cohort study analyzed 2,229 pregnant women with syphilis from the National PMTCT System of Taizhou City (2013–2023). Standardized treatment was defined as 3 weekly intramuscular benzathine penicillin doses (2.4 MU each). Multivariable logistic regression adjusted for gestational age, maternal age, and comorbidities was used to analyze the outcomes.

Results: A total of 1,651 women (74.1%) received standardized therapy and the risk of adverse pregnancy outcomes was significantly lower in this group compared to those with non-standardized treatment: perinatal death (0.55% vs. 2.60%), congenital syphilis (0.24% vs. 2.60%), preterm birth/low birth weight (7.81% vs. 16.78%), and total adverse outcomes (8.60% vs. 38.75%) (all p < 0.001). Adjusted analysis demonstrated 58% risk reduction with standardized treatment (aOR = 0.42, 95% CI: 0.31–0.57, p < 0.001). Early initiation (≤ 20 weeks) enhanced efficacy (aOR = 2.12, 95% CI: 1.45–3.10, p < 0.001), with married (aOR = 2.41) and educated women (aOR = 1.89) showing higher adherence.

Conclusions: Standardized penicillin regimens significantly mitigate adverse pregnancy outcomes by 58%, emphasizing early diagnosis, timely treatment, and targeted patient education for PMTCT success. Marital status and education level were independently associated with treatment adherence.