Congenital syphilis in Portugal, 2015-2024: Temporal-spatial characterization and gaps in prevention of vertical transmission.

Aligned with the increasing trend observed across the EU/EEA, congenital syphilis (CS) cases have risen in Portugal, which has the third highest rate per 100000 live births in the EU/EEA. This study aimed to analyse CS cases reported in Portugal, focusing on pregnancy monitoring and antenatal screening to identify gaps in preventing vertical transmission of syphilis. We conducted a descriptive study, including confirmed CS cases reported in Portugal from 2015 to 2024. We calculated annual incidence per 100000 live births and the proportion of pregnancies monitored and antenatal screenings performed. During 2015-2024, 99 confirmed CS cases were reported, 64.6% in infants under 1 month of age. The incidence of CS increased eightfold from 2016 to 2024. Among mothers of CS cases, 67.7% had pregnancies classified as monitored; of these, 77.6% had a record of antenatal screening, and 88.5% of those screened tested positive. These findings highlight potential fragilities in antenatal care, diagnosis and treatment, contributing to the resurgence of CS in Portugal. Addressing missed opportunities for prevention requires improving maternal healthcare, strengthening surveillance systems, and ensuring the timely treatment of pregnant people and their partners, in order to reverse this trend and move towards the elimination of vertical transmission of syphilis.