Prenatal Syphilis Screening Among Pregnant Medicaid Enrollees by Sexually Transmitted Infection History and Race/Ethnicity.

BACKGROUND: Congenital syphilis can cause severe morbidity, including miscarriage and stillbirth, and rates are increasing rapidly within the US. However, congenital syphilis can be prevented with early detection and treatment of syphilis during pregnancy. Current screening recommendations hold that all women should be screened early in pregnancy, while women at elevated risk of 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.

OBJECTIVES: To examine associations between the odds of prenatal syphilis screening and sexually transmitted infection (STI) history or other patient characteristics, in three states with elevated rates of congenital syphilis.

STUDY DESIGN: We used Medicaid claims data from Kentucky, Louisiana, and South Carolina from 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 patient health history, demographic factors, and Medicaid enrollment history. Patient history was established using a 4-year lookback of Medicaid claims data; in State A, STI surveillance data was used to improve STI history.

RESULTS: Prenatal syphilis screening rates varied by state, ranging from 62.8-85.1% for deliveries by women without a recent history of STI and from 78.1-91.1% for deliveries by women with prior STI. For the main outcome, syphilis screening at any time in pregnancy, deliveries associated with prior STI had 1.09-1.37 times higher adjusted odds ratios (aOR). Deliveries by women with continuous Medicaid throughout the first trimester also had higher odds of syphilis screening at any time (aOR = 2.45-3.15). Among deliveries by women with a prior STI, only 53.6-63.6% received first trimester screening and this rate was still just 55.0-69.5% when considering only deliveries by women with a prior STI and full first trimester Medicaid coverage. Fewer delivering women received third trimester screening (20.3-55.8% of women with prior STI). Compared to deliveries by White women, deliveries by Black women had lower odds of first trimester screening (aOR = 0.85 in all states) but higher odds of third trimester screening (aOR = 1.23-2.03), potentially impacting maternal and birth outcomes. For State A, linkage to surveillance data doubled the rate of prior STI detection, as 53.0% of deliveries by women with a prior STI would not have had STI history detected using Medicaid claims alone.

CONCLUSIONS: Prior STI and continuous pre-conception Medicaid enrollment were associated with higher rates of syphilis screening, but Medicaid claims alone do not fully capture patient STI history. Overall screening rates were lower than would be expected, given that all women should undergo prenatal screening, but rates in the third trimester were particularly low. Notably, there are gaps in early screening for non-Hispanic Black women, who had lower odds of first trimester screening compared to non-Hispanic White women despite being at elevated risk of syphilis.