Syphilis Exposure During Pregnancy and Childhood Hospital Admissions in Brazil

While the short-term impacts of congenital syphilis are well documented, the long-term outcomes and effects on children exposed to syphilis during pregnancy but without congenital infection detected at birth remain unclear.

To compare the rates of all-cause hospitalization in children younger than 5 years between those exposed to syphilis during pregnancy (with and without congenital syphilis) and those unexposed to syphilis during pregnancy.

Population-based study using linked data from the Center of Data and Knowledge Integration for Health Birth Cohort, including singleton live births between January 1, 2011, and December 31, 2015. Children were followed up until age 5 years, death, or December 31, 2018, whichever occurred first. Data were made available in 2020 and analyzed between March and September 2024.

In this study, syphilis during pregnancy was categorized into 3 groups: (1) maternal syphilis, (2) congenital syphilis, and (3) no exposure, for those without syphilis records.

Primary outcomes were: (1) general and age-stratified first hospital admission rates, (2) length of stay for the first hospital admission, and (3) International Classification of Diseases and Related Health Problems, Tenth Revision diagnoses of the first hospitalization. Secondary outcomes included: (1) recurrent hospital admissions and (2) mortality.

The study included 8 286 867 singleton births, with 30 039 exposed to maternal syphilis (15 482 [51.5%] male, 7642 [25.4%] Asian, 2442 [8.1%] Black, and 16 930 [56.4%] Pardo [denotes individuals who are White and Indigenous, White and Black, Black and Indigenous, or Black and another race]) and 36 443 with congenital syphilis (18 286 [50.2%] male, 6977 [19.1%] Asian, 3769 [10.3%] Black, 16 930 [56.4%] Pardo). Exposed births were more prevalent in Black, single, and less educated women. Compared with children with no exposure, those with congenital syphilis had an increased risk of first hospitalization (hazard ratio [HR], 6.19; 95% CI, 6.11-6.28), as did those exposed to maternal syphilis (HR, 1.90; 95% CI, 1.86-1.94). The highest risk of first hospitalization was observed in the first month of life, among those with congenital syphilis (HR, 11.53; 95% CI, 11.36-11.70). Although the risk decreased with age, children exposed to syphilis continued to have higher hospitalization rates than the nonexposed group until the age of 36 months. Live-born children exposed to syphilis during pregnancy also had more and longer hospital admissions. Those with congenital syphilis had a lower prevalence of respiratory and digestive diagnoses than those with maternal syphilis and the nonexposed group.

In this cohort study, we observed that those children exposed to syphilis during pregnancy, even without congenital syphilis detected at birth, had a higher risk of hospital admission and were hospitalized for longer periods. These findings underscore the need for close monitoring of exposed children and emphasize the importance of preventing syphilis in women of childbearing age.