Risk factors and adverse outcomes associated with syphilis infection during pregnancy

The prevalence of syphilis infection in pregnancy is increasing at an alarming rate.

This study aimed to evaluate sociodemographic risk factors and adverse pregnancy outcomes associated with syphilis infection during pregnancy in a current US population of live births.

This was a retrospective analysis of the Centers for Disease Control and Prevention, Natality Live Birth database for the years 2016 to 2019. All live births were eligible for inclusion. Deliveries with missing data on syphilis infection were excluded. We analyzed the database comparing pregnancies complicated by maternal infection with syphilis with those without infection. Several maternal sociodemographic factors and adverse pregnancy and neonatal outcomes were compared between the 2 groups. Multivariable logistic regression was performed to evaluate the association of these factors with syphilis infection in pregnancy, and adverse pregnancy and neonatal outcomes while adjusting for potential confounders. Data were presented as adjusted odds ratios with 95% confidence intervals.

Of the 15,341,868 births included, 17,408 (0.11%) were complicated by maternal infection with syphilis. Concurrent infection with gonorrhea was associated with the highest risk of syphilis in pregnancy (adjusted odds ratio, 7.24; 95% confidence interval, 6.79-7.72). Low educational attainment (less than high school: adjusted odds ratio, 4.40; 95% confidence interval, 3.93-4.92), non-Hispanic Black race/ethnicity (adjusted odds ratio, 3.81; 95% confidence interval, 3.65-3.98), and Medicaid insurance (adjusted odds ratio, 2.13; 95% confidence interval, 2.03-2.23) were also associated with a significantly increased risk of infection. Syphilis infection was associated with an increased risk for preterm birth (<37 weeks: adjusted odds ratio, 1.25; 95% confidence interval, 1.20-1.31; <32 weeks: adjusted odds ratio, 1.26; 95% confidence interval, 1.16-13.7), low birthweight (adjusted odds ratio, 1.34; 95% confidence interval, 1.28-1.40), congenital malformations (adjusted odds ratio, 1.43; 95% confidence interval, 1.14-1.78), low 5-minute Apgar scores (adjusted odds ratio, 1.29; 95% confidence interval, 1.19-1.41), neonatal intensive care unit admission (adjusted odds ratio, 2.19; 95% confidence interval, 2.11-2.28), immediate ventilation (adjusted odds ratio, 1.48; 95% confidence interval, 1.39-1.57), and prolonged ventilation (adjusted odds ratio, 1.58; 95% confidence interval, 1.44-1.73).

We identified several risk factors and adverse pregnancy outcomes associated with syphilis infection in pregnancy. Given the concerning rise in prevalence of pregnancy infections, public health strategies aimed at infection prevention and access to timely screening and treatment to reduce associated adverse pregnancy outcomes are urgently needed.