Modest improvement in universal prenatal syphilis screening five years after legislation enacted.

Introduction: The rate of congenital syphilis increased 498% in Michigan during 2017-2023. Congenital syphilis can be averted if a pregnant woman is screened and treatment initiated ≥30 days before delivery. To strengthen prevention strategies in Michigan, legislation was passed in December 2018 requiring universal prenatal syphilis screening in the first and third trimesters. Methods: We analyzed de-identified health claims data from women enrolled in Michigan Medicaid who delivered an infant during 2017-2023. Timing of syphilis screening was estimated by subtracting the date of screening from the date of delivery. Percentage of pregnant women 1) ever screened (280 - 0 days preceding delivery); 2) screened during approximately the first or second trimesters (280 - 94 days preceding delivery) and in the early third trimester (93 - 30 days preceding delivery), jointly and separately; and 3) screened <30 days preceding delivery were calculated and compared pre- (2017) versus 5-years post- (2023) legislation. Absolute percentage changes were evaluated by demographic characteristics, including residence in counties with elevated syphilis among reproductive-aged women (>4.6 cases per 100,000 people); changes <10% were considered stable. Results: Over the 7-year study period, 211,289 deliveries were evaluated; approximately half the sample were Non-Hispanic White, half were younger than 27 years (median age), and three-quarters resided in counties with elevated syphilis rates. Screening for syphilis at least once during pregnancy was common (average, 92.0%), as was screening during the first or second trimester (82.3%); screening only <30 days preceding delivery was infrequent (8.9%); percentages were stable pre- and post-legislation (-1.8%, -4.0%, and +1.8%, respectively). Screening in the early third trimester increased post-legislation (37.1% to 53.7%), as did screening in the first or second trimester and repeated in the early third trimester (30.1% to 45.0%). Screening increases were less pronounced in counties with higher syphilis burden compared with lower burden areas. Findings were similar across age and race/ethnicity subgroups. Conclusion: Repeat syphilis screenings have increased following legislation requiring universal first and third trimester testing. Strategies to raise awareness of the necessity and value of repeat prenatal syphilis testing, especially in the early third trimester, are important to strengthen congenital syphilis prevention efforts.