TOPLINE:

A history of adequately treated syphilis before pregnancy is associated with more than a 100-fold increase in congenital syphilis risk, with rates of 6806 per 100,000 live births compared with 70 per 100,000 in those without prior history. Maternal syphilis reinfection during pregnancy occurred in nearly 18% of women with prior treated syphilis compared with less than 1% without prior history.

METHODOLOGY:

• Researchers conducted a retrospective cohort study of 57,925 deliveries occurring after 20 weeks of gestation within a large multihospital healthcare system across Louisiana in the US from January 2015 to December 2023.
• Pregnant individuals were stratified based on whether there was a pre-pregnancy history of adequately treated syphilis infection, defined as prior positive rapid plasma reagin (RPR) test and positive treponemal antibody test with completion of appropriate antibiotic course according to CDC guidelines.
• Propensity score full matching was performed retaining all 382 patients with prior treated syphilis, with covariates including maternal age, neighborhood Area Deprivation Index, tobacco use, insurance payer, prenatal visits, and gestational age at delivery.
• Primary outcome was congenital syphilis as defined by CDC case criteria; secondary outcomes included maternal syphilis infection during pregnancy and neonatal administration of a single intramuscular dose of penicillin G.
• Serofast status was defined as initial prenatal RPR titer of 1:4 or less, with evidence of appropriate treatment at least 12 months prior and with at least fourfold decrease in titers and no concern for reinfection based on clinical assessment.

TAKEAWAY:

• Congenital syphilis occurred in 26 of 382 (6.8%) pregnancies in women with history of treated syphilis compared with 40 of 57,543 (0.1%) without (adjusted odds ratio [aOR], 19.61; 95% CI, 4.57-84.25).
• Maternal syphilis reinfection occurred in 68 of 382 (17.8%) with prior treated syphilis compared with 258 of 57,543 (0.4%) without (aOR, 11.92; 95% CI, 5.89-24.10).
• Neonates born to women with prior treated syphilis were more likely to receive a single intramuscular prophylactic dose of penicillin G before discharge than those born to women without prior syphilis (58 of 382 vs 122 of 57,543; aOR, 17.47; 95% CI, 6.90-44.27).
• Among patients with history of adequately treated syphilis, congenital syphilis occurred in 12 of 154 (7.8%) pregnancies in serofast women compared with 14 of 228 (6.1%) pregnancies in seronegative women (OR, 1.29; 95% CI, 0.53-3.11).

IN PRACTICE:

“A history of adequately treated syphilis infection before pregnancy was associated with dramatically increased risks of congenital syphilis and maternal syphilis reinfection during pregnancy. These findings challenge assumptions about the protective effects of prior treatment and support enhanced surveillance strategies for this high-risk population,” wrote the authors of the study.

SOURCE:

The study was led by J. Drew Toppin, MD, MPH, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Ochsner Health System in New Orleans. It was published online in Obstetrics & Gynecology.

LIMITATIONS:

The retrospective design limits causal inference. Seronegative patients with unreported or undocumented syphilis history may have been missed given that the institution employed the classic nontreponemal test screening algorithm, though substantial effect from such omissions would bias toward the null and potentially underestimate the exposure effect. The definition of adequately treated relied primarily on medical record review and may not identify all relevant treatment nuances, including treatment through public health departments or other institutions. The overall cohort reflects the demographics of a high-incidence southern US healthcare system, which may limit generalizability. The exposed group size limits statistical power for subgroup analyses. Date of prior syphilis treatment was not available for all patients, precluding analysis of time since treatment as a predictor of reinfection risk. Stage of prior syphilis infection (primary, secondary, or latent) was not consistently documented in the electronic health record, as treatment frequently occurred through external clinics.

DISCLOSURES:

The authors reported having no potential conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.