Rising Stillbirth Rates Related to Congenital Syphilis in the United States From 2016 to 2022.

Objective: To identify trends in stillbirth rates attributed to congenital syphilis in the United States by describing congenital syphilis-related stillbirths and comparing characteristics of pregnant people who had congenital syphilis-related stillbirths with those of people who had preterm and full-term liveborn neonates with congenital syphilis.

Methods: Cases of congenital syphilis reported to the Centers for Disease Control and Prevention during 2016-2022 were analyzed and categorized as stillbirth, preterm live birth (before 37 weeks of gestation), or term live birth (37 weeks or later). Cases with unknown vital status or gestational age were excluded. Frequencies were calculated by pregnancy outcome, including pregnant person demographics; receipt of prenatal care; syphilis stage and titer; and timing of prenatal care, testing, and treatment.

Results: Overall, 13,393 congenital syphilis cases with vital status and gestational age were reported; of these, 853 (6.4%) were stillbirths. The number of congenital syphilis-related stillbirths increased each year (from 44 to 231); the proportion of congenital syphilis cases resulting in stillbirth ranged from 5.2% to 7.5%. Median gestational age at delivery for stillborn fetuses was 30 weeks (interquartile range 26-33 weeks). People with congenital syphilis-related stillbirths were more likely to have titers at or above 1:32 (78.9% vs 45.5%; P <.001) and to have received no prenatal care (58.4% vs 33.1%; P <.001) than people with liveborn neonates with congenital syphilis. The risk of stillbirth was twice as high in persons with secondary syphilis compared with those with primary syphilis (11.5% vs 5.7%, risk ratio 2.00; 95% CI, 1.27-3.13). Across all congenital syphilis cases, 34.2% of people did not have a syphilis test at their first prenatal visit.

Conclusion: Stillbirths occurred in more than 1 in 20 pregnancies complicated by congenital syphilis. Risk factors for stillbirth included high titers, secondary stage, and lack of prenatal care. If the prevalence of congenital syphilis continues to rise, there will be a corresponding increase in the overall stillbirth rate nationally.