[Association of illicit drug use in pregnant women and congenital syphilis in a public hospital in Mexico]. / Asociación del consumo de drogas ilícitas en mujeres embarazadas y sífilis congénita en un Hospital Público de México.

We conducted a nested case-control study within a cohort with the aim of studying the association between illicit drug use and congenital syphilis (CS). Cases were diagnosed based on treponemal and non-treponemal tests conducted both in the mother and the newborn (NB). Multivariate analysis with logistic regression was performed. A total of 6171 births with a mean gestational age of 37.8 weeks were recorded and 62 CS events were diagnosed (incidence 10.5 events/1000 NB). Associated maternal factors were illicit drug use (OR 14.08, 95% CI 1.19-166.6), <5 prenatal visits (OR 2.9, 95% CI 1.12-7.53), more than two sexual partners (OR 3.76, 95% CI 1.62-8.71) and professional education level (OR 0.06, 95% CI 0.005-0.85). Among the mothers of the cases presented, the prevalence of illicit drug use was 22.6% and the most frequent drugs were methamphetamines and cannabis.