Identifying missed prevention opportunities: maternal and congenital syphilis in hospital records and birth certificates in California from 2011 to 2021.

OBJECTIVE: To examine maternal risk factors for congenital syphilis (CS). STUDY DESIGN: We used a retrospective, population-based cohort of births in California (2011-2021) with linked birth certificates and hospital records. Modified Poisson regression models with robust standard errors were used to assess characteristics associated with CS. Among dyads with CS, maternal syphilis documentation was also examined. RESULTS: Of 4,481,096 births, 4659 (0.1%) had maternal syphilis without CS, and 2608 (0.06%) had both maternal syphilis and CS. CS was associated with having public insurance, tobacco use, drug use disorders, and residence in fringe-metro or medium/small-metro counties. Among CS dyads, 62.0% had no maternal syphilis documentation. There was a lower risk of no maternal syphilis documentation among those with <12th grade education; non-Hispanic Black identity; tobacco, cannabis, or drug use disorders; mental health conditions; and inadequate prenatal care. CONCLUSIONS: Universal prenatal syphilis screening, treatment, and documentation are essential to preventing CS.