Lack of prenatal care, testing fueling rise in congenital syphilis-related stillbirths

Key takeaways:

• U.S. cases of congenital syphilis-related stillbirths rose each year from 2016 to 2022.
• Risk factors for stillbirth included high syphilis antibody titers, secondary syphilis and receiving no prenatal care.

The number of congenital syphilis-related stillbirths increased annually from 2016 to 2022 in the U.S. while the proportion of cases resulting in stillbirth remained stable, researchers reported in Obstetrics & Gynecology.

In an analysis of congenital syphilis cases reported to the CDC, researchers also found that lack of prenatal care and inadequate syphilis testing were the most likely contributors to the rising stillbirth rate.

“Although diagnosis and treatment of syphilis before pregnancy prevents all congenital syphilis, early identification of syphilis during pregnancy and timely treatment with the appropriate benzathine penicillin G regimen can prevent 98% of congenital syphilis cases,” Aliza Machefsky, MD, assistant professor in the department of gynecology and obstetrics at Emory University School of Medicine, and colleagues wrote. “Yet, congenital syphilis cases have continued to rise over the past decade in the United States, with more than nine times the cases reported in 2022 as in 2013.”

Machefsky and colleagues evaluated 13,393 congenital syphilis cases reported to the CDC from 2016 to 2022 with data on vital status and gestational age. Researchers calculated stillbirth frequency by pregnancy outcome, maternal demographics, prenatal care receipt, syphilis stage and titer, prenatal care timing, testing and treatment.

Overall, 6.4% of cases were stillbirths, 28.5% were preterm live births (< 37 weeks’ gestation) and 65.2% were full-term live births.

Median gestational age at delivery for all congenital syphilis-related stillbirths was 30 weeks. The number of congenital syphilis-related stillbirths rose each year from 44 in 2016 to 231 in 2022. The proportion of congenital syphilis cases reported as stillbirths varied from 5.2% to 7.5% during the same period.

Compared with women with congenital syphilis who had live births, those with congenital syphilis-related stillbirths had a higher likelihood of having antibody titers at or above 1:32 vs. antibody titers of 1:16 or lower (RR = 5.19; 95% CI, 4.28-6.29; P < .001), as well as a greater likelihood of receiving no prenatal care vs. at least one prenatal visit (RR = 2.64; 95% CI, 2.31-3.01; P < .001). In addition, women with secondary syphilis, which researchers noted was less common, had twice the risk for congenital syphilis-related stillbirth compared with women with primary syphilis (RR = 2; 95% CI, 1.27-3.13).

The researchers also highlighted a need for more testing for congenital syphilis, noting that 34.2% of women did not receive a syphilis test at their first prenatal visit.

ACOG recommends syphilis screening three times during pregnancy regardless of risk: at the initial prenatal visit, during the third trimester and at delivery.

“Efforts to ensure syphilis screening at the first prenatal visit or encounter with the health care system might allow for diagnosis and treatment earlier in pregnancy, potentially preventing congenital syphilis,” the researchers wrote.”