High burden of maternal and congenital syphilis in Lima, Peru: an epidemiological analysis from 2023-2025

Congenital syphilis remains a preventable cause of fetal and neonatal morbidity and mortality, despite the availability of inexpensive diagnostics and effective treatment. We aimed to evaluate the maternal and congenital syphilis burden at the Instituto Nacional Materno Perinatal, Peru's national referral center for maternal and perinatal care.

We conducted a retrospective analysis of aggregated, de-identified surveillance data from January 2023 to December 2025. Maternal prevalence and congenital syphilis incidence were calculated and compared with World Health Organization (WHO) elimination benchmarks.

Among 59,568 pregnant women screened, maternal syphilis prevalence ranged between 1·0% and 1·2% of all women screened. Across 36,094 live births, congenital syphilis incidence ranged between 191 and 259 per 100,000 live births, consistently exceeding the WHO target of 50 per 100,000 live births. More than half of maternal infections were diagnosed at outside facilities before referral. Reported treatment coverage exceeded 90% among mothers and 100% among infants in all years.

The prevalence of congenital syphilis exceeded WHO elimination benchmarks despite stable maternal prevalence, highlighting gaps in timely diagnosis and linkage between diagnosis and treatment.