Maternal and perinatal risk factors associated with congenital syphilis

Mother-to-child transmission of syphilis remains an important global public health problem. Untreated intrauterine infection may result in adverse events for the fetus or newborn (NB). Maternal risk factors, such as prenatal care, early diagnosis, and appropriate treatment, significantly impact the likelihood of vertical transmission of syphilis. The purpose of this review is to evaluate maternal risk factors for congenital syphilis and the characteristics of exposed NB.

A total of 14 studies were evaluated, including 8 cohort studies, 4 cross-sectional and 2 control cases. A total of 12,230 women were included, with confirmed or highly probable congenital syphilis outcome, and 2285 NB. The studies evaluated risk factors for congenital syphilis, which were maternal, demographic, obstetric factors and characteristics of the exposed NB.

Included in the risk factors studied, inadequate prenatal care and late onset, as well as inadequate or late treatment of maternal syphilis were significant risk factors for the outcome of congenital syphilis. When the time set of maternal diagnosis was correlated with neonatal infection, there was a tendency to worsen prognosis (more infected NB) in women diagnosed later in pregnancy, as well as in women who underwent few prenatal consultations and inadequate treatment. Women with recent syphilis with high VDRL titres had a higher rate of vertical transmission. The prior history of syphilis with adequate treatment was identified as a protective factor, resulting in lower rates of congenital syphilis. Among the epidemiological and demographic aspects surveyed, it was observed that young age, lower schooling, unemployment, low family income and no fixed residence were associated with higher risk of congenital syphilis.

The association of syphilis with adverse socio-economic conditions and inadequate prenatal care suggests that the improvement of the population's living conditions and equitable access to quality health services may have an impact on the reduction of congenital syphilis.