Prenatal syphilis screening among pregnant Medicaid enrollees by sexually transmitted infection history as well as race and ethnicity

BACKGROUND: Congenital syphilis can cause severe morbidity, including miscarriage and stillbirth, and rates are increasing rapidly within the United States. However, congenital syphilis can be prevented with early detection and treatment of syphilis during pregnancy. Current screening recommendations propose that all women should be screened early in pregnancy, whereas women with elevated risks for congenital syphilis should be screened again later in pregnancy. The rapid increase in congenital syphilis rates suggests that there are still gaps in prenatal syphilis screening. OBJECTIVE: This study aimed to examine associations between the odds of prenatal syphilis screening and sexually transmitted infection history or other patient characteristics across 3 states with elevated rates of congenital syphilis. STUDY DESIGN: We used the Medicaid claims data from Kentucky, Louisiana, and South Carolina for women with deliveries between 2017 and 2021. Within each state, we examined the log-odds of prenatal syphilis screening as a function of the mother's health history, demographic factors, and Medicaid enrollment history. Patient history was established using a 4-year lookback period of the Medicaid claims data; in state A, sexually transmitted infection surveillance data were used to improve the sexually transmitted infection history. RESULTS: The prenatal syphilis screening rates varied by state, ranging from 62.8% to 85.1% of deliveries to women without a recent history of sexually transmitted infections and from 78.1% to 91.1% of deliveries to women with a previous sexually transmitted infection. For the main outcome of syphilis screening at any time during pregnancy, deliveries associated with previous sexually transmitted infections had 1.09 to 1.37 times higher adjusted odds ratios of undergoing screening. Deliveries to women with continuous Medicaid coverage throughout the first trimester also had higher odds of syphilis screening at any time (adjusted odds ratio, 2.45–3.15). Among deliveries to women with a previous sexually transmitted infection, only 53.6% to 63.6% underwent first-trimester screening and this rate was still just 55.0% to 69.5% when considering only deliveries to women with a previous sexually transmitted infection and full first-trimester Medicaid coverage. Fewer delivering women underwent third-trimester screening (20.3%–55.8% of women with previous sexually transmitted infection). Compared with deliveries to White women, deliveries to Black women had lower odds of first-trimester screening (adjusted odds ratio, 0.85 in all states) but higher odds of third-trimester screening (adjusted odds ratio, 1.23–2.03), potentially impacting maternal and birth outcomes. For state A, linkage to surveillance data doubled the rate of detection of a previous sexually transmitted infection because 53.0% of deliveries by women with a previous sexually transmitted infection would not have had sexually transmitted infection history detected using Medicaid claims alone. CONCLUSION: A previous sexually transmitted infection and continuous preconception Medicaid enrollment were associated with higher rates of syphilis screening, but Medicaid claims alone do not fully capture the sexually transmitted infection history of patients. The overall screening rates were lower than would be expected given that all women should undergo prenatal screening, but the rates in the third trimester were particularly low. Of note, there are gaps in early screening for non-Hispanic Black women who had lower odds of first-trimester screening when compared with non-Hispanic White women despite being at elevated risk for syphilis.