# Prenatal Syphilis Screening Mandates and Maternal Syphilis Case Detection

## TL;DR

Expanding syphilis screening mandates during late pregnancy briefly increased case detection but did not lead to long-term improvements without additional support.

## Contribution

The study evaluates the impact of expanded prenatal syphilis screening mandates on case detection using a large-scale cross-sectional analysis.

## Key findings

- Expanded screening mandates led to a 26% increase in maternal syphilis case detection in the first quarter after enactment.
- The effect declined within a year and was no longer significant.
- Complementary efforts are needed for sustained impact on syphilis detection.

## Abstract

What is the association between mandates requiring prenatal syphilis screening in the third trimester and delivery and maternal syphilis case detection?

In this cross-sectional study including 16.3 million live births and 20 961 reported syphilis cases between 2012 and 2022 in the US, maternal syphilis case detection increased by a statistically significant 26% in the first quarter after mandates at the third trimester and delivery were enacted. The magnitude of this effect declined within the following year, although it remained positive.

Mandates for syphilis screening later in pregnancy may briefly increase maternal syphilis case detection but are unlikely to generate sustained impact on their own without complementary supports for screening and treatment.

This cross-sectional study evaluates the effectiveness of expanding prenatal syphilis screening mandates on syphilis case detection during pregnancy.

Rates of congenital syphilis in the US have surged over the past decade, despite most states having long-standing mandates requiring clinicians to offer syphilis screening early in pregnancy. Gaps in screening coverage remain, and first-trimester screening alone may miss cases. Several professional bodies now recommend repeat screening in the third trimester and at delivery. Evidence on the impact of expanded prenatal syphilis screening mandates on case detection is limited.

To evaluate the effectiveness of expanding prenatal syphilis screening mandates on syphilis case detection during pregnancy.

Birth certificate data from 33 US states between 2012 and 2022 were analyzed using a staggered difference-in-differences design. Maternal syphilis case detection in 4 states that enacted mandates for third-trimester and delivery screening (Arizona, Georgia, Louisiana, and Michigan) were compared with 29 control states without such mandates during this period. The new mandates required all pregnant people be offered third-trimester screening. Three of the states further required that individuals at high risk of syphilis infection be offered screening again at delivery, and 1 state required universal delivery screening. To ascertain whether expanded mandates were associated with changes in screening coverage, inpatient discharge records from 1 mandate expansion state (Georgia) were analyzed. Data were analyzed from December 2024 to September 2025.

Passage of a universal syphilis screening mandate in the third trimester and a high-risk or universal mandate at delivery between 2012 and 2022.

Maternal syphilis case detection (cases per 100 000 live births) and the share of deliveries receiving syphilis screening.

The study sample included 16.3 million live births and 20 961 reported syphilis cases between 2012 and 2022 in 4 mandate expansion states and 29 control states. Expanded screening mandates were associated with a 26% (95% CI, 3-53) increase in maternal syphilis case detection in the first quarter after enactment. The increase in case detection attenuated thereafter and was no longer significant within 1 year (11%; 95% CI, −17 to 48; P = .48).

In this study, expanded prenatal syphilis screening mandates may improve syphilis case detection in the near-term but are unlikely to have sustained impact without complementary efforts, such as those that facilitate clinician adherence and ensure patient access to and completion of treatment.