Congenital syphilis marks the failure of health systems in the context of intersecting social and structural determinants of health.^1–3 In the United States (US), there were 3,755 cases of CS in 2022, a 1,121% increase from 335 cases in 2012.³ Lack of timely testing due to barriers to prenatal care and inadequate treatment among pregnant people with syphilis comprised 88% of the missed opportunities to prevent CS nationally in 2022.⁴ In Oregon, there were no cases of CS in 2013 and 37 (65.7 cases per 100,000 live births) in 2022. Concurrently, the rate of primary and secondary syphilis among people assigned female at birth in Oregon increased from 1.6 in 2015 to 16.1 cases per 100,000 population in 2022. There were 18 cases of syphilis during pregnancy per 100,000 live births in 2013 compared to 210 cases per 100,000 live births in 2021.⁵ These increases in syphilis among people assigned female at birth and infants are occurring in the context of significant increases methamphetamine and fentanyl overdose morbidity and mortality (in 2022, the crude rates of methamphetamine and fentanyl overdose mortality were 20 and 19 per 100,000, respectively)⁶ and increasing rates of houselessness in Oregon.⁷

While inadequate prenatal care, delayed testing, and untreated syphilis during pregnancy consistently emerge as strongest predictors of CS,⁴ additional individual-level factors among pregnant people include: early syphilis (comprised of primary, secondary, and asymptomatic nonprimary nonsecondary syphilis occurring in the prior 12 months) compared to late syphilis (Treponema pallidum infections of greater than a year’s duration),⁸ lack of access to prenatal care,^4,9 substance use^9,10 (specifically methamphetamine use),¹¹ housing instability,^9,11 engaging in anonymous sex,¹² having multiple sex partners,¹² transactional sex,¹² low educational attainment,¹³ and mental health challenges.¹⁰ The relationship between incarceration (current or history of) and intimate partner violence with increased risk of CS is less consistent across studies.^9,10

Understanding the social context and the root causes of CS is crucial to ending the expanding epidemic. Community-level (county, census tract, or ZIP code-level) factors associated with an increased risk of CS in previous studies and predictive models include: female poverty,¹⁴ female educational attainment,¹⁴ income inequality,¹⁵ population proportions of Hispanic, non-Hispanic Black, Native Hawaiian/Pacific Islander above the median,¹⁵ insurance status,¹⁴ urbanicity,^15,16 and violent crime.¹⁶ To guide public health programs and policy to prevent CS, we assessed individual-level and county-level factors associated with CS cases in Oregon from 2013 through 2021.

We conducted a retrospective analysis of individual- and county-level factors associated with CS cases among pregnant people with syphilis in Oregon from 2013–2021.

From 2013 to 2021, there were 343 pregnant people diagnosed with syphilis. The median age was 27 years (range: 16–43 years; Table 1). Approximately half identified as white (n=181), a quarter lived in rural areas (n=80), and 55% were diagnosed between 2019–2021 (n=189). Over 60% had late or unknown duration syphilis (n=212), 10% reported a partner with early syphilis prior to their diagnosis (n=33), and 14% had a previous syphilis diagnosis (n=48). Nine (n=31) and 18% (n=60) were diagnosed with gonorrhea and chlamydia respectively in the two years before their syphilis diagnosis, while 6% had HCV prior to their syphilis diagnosis (n=20). A quarter reported ever using injection drugs (n=88) or having a partner who used injection drugs (n=85), and over 40% had ever been involved in the correctional system (n=149).

Among 343 pregnant people with syphilis in Oregon, the risk of being associated with a case of CS was greater among people with a history of IDU or corrections involvement and among pregnant people residing in counties with higher levels of socioenvironmental inequities. The increase in risk with heightened county-level socioenvironmental challenges was greatest among those with a history of corrections involvement. We observed a protective effect of a prior diagnosis of gonorrhea even after eliminating diagnoses within one month of the syphilis diagnosis. Gonorrhea may be a salient marker of risk such that pregnant people with a history of gonorrhea are more likely to be screened for syphilis during pregnancy²⁴ leading to diagnosis and treatment. We did not see the same effect for a prior chlamydia diagnosis. In Oregon, chlamydia diagnoses are not routinely investigated by LPHAs while gonorrhea diagnoses are, particularly among people who can become pregnant, which may explain this observed difference.

Since 2015, OHA has recommended routine, universal syphilis screening in pregnancy at the first presentation to prenatal care, in the early third trimester, and at delivery.²⁵ As of April 2024, the American College of Obstetricians and Gynecologists also recommends routine, universal syphilis screening at three time points during pregnancy.²⁶ Based on our data, 23/95 (24.2%) pregnant people associated with a case of CS experienced seroconversion or reinfection during pregnancy and did not receive timely diagnosis or treatment. Routine third trimester screening may have detected these seroconversions or reinfections earlier leading to timely diagnosis and treatment and aversion of almost one-quarter of CS cases. Screening three times during pregnancy has been shown to be cost-effective even before the large increase in CS in the US²⁷ and cost-avoidant during an outbreak of CS.²⁸

Furthermore, universal screening in pregnancy acknowledges that the risk of syphilis acquisition may result from a partner or a sexual network rather than the behaviors of pregnant people themselves.^29,30 In fact, in the current analysis, we found that pregnant people who reported partners who used injection drugs were 1.5 times as likely to be associated with a case of CS compared to those who did not. This association was not statistically significant in multivariable analysis, however. Oregon LPHAs endeavor to provide partner services to all pregnant people and pregnancy-capable with syphilis. Partner testing and treatment is critical to avoiding reinfection and client and partner interviews provide important contextual information for CS prevention.

Clinician education and comfort around diagnosing and treating syphilis are also crucial in preventing CS.³¹ Pregnant people diagnosed with syphilis in hospital or emergency department settings were more likely to be associated with a case of CS compared to other healthcare settings.¹² OHA promotes the policy that for pregnant people, all visits are prenatal visits, so that when pregnant people attend the emergency room or an urgent care clinic, access drug use health programs (e.g., substance use disorder treatment programs, syringe service programs), or are admitted to a carceral setting, they should have prenatal labs drawn, including for syphilis, when their prenatal care status is uncertain or unknown. Conversely, all people pregnancy-capable with syphilis should be tested for pregnancy and where possible pregnancy status should be reported to local and state public health departments concurrently with laboratory and clinician syphilis case reports.

From 2020 to 2021, Oregon experienced a 50% increase in diagnoses of primary and secondary syphilis cases and an 80% increase in diagnoses of primary and secondary syphilis among people assigned female at birth. Like others, we found that risk-based screening would miss almost 50% of cases of syphilis among people assigned female at birth.²⁹ Therefore, OHA recommends universal screening²⁵ for all sexually active adults 45 years of age and younger who have not been screened for syphilis since January 1, 2021. OHA provides guidance for who should be screened more frequently, based on individual-level (e.g, housing status, substance use, corrections involvement, prior HIV/STI or HCV diagnosis), partner-level (e.g., housing status, substance use, corrections involvement, gender of partners’ sex partners), and contextual-level (e.g., location of care including sexual health and family planning clinics, carceral settings, emergency rooms, substance use disorder treatment programs) indications.

While injection drug use, corrections involvement, and county-level socioenvironmental inequities do not explain all the variation in the outcome of CS and may operate through multiple causal pathways, the multilevel analyses and PAFs ranging from 15–21% provide evidence for addressing substance use, incarceration, and the role that poverty, mental health, trauma, and community violence play in the syphilis epidemic. Substance use and corrections involvement at the individual- and county-level affect whether people might access or persist in prenatal care. In the US, there is a legacy of curtailing reproductive autonomy through the medical system, particularly for pregnant people who are Black, Indigenous, Latinx, and Pacific Islander, are immigrants, are experiencing poverty, use substances, have mental health challenges or other disabilities, or are or have been involved in the criminal justice system.^31s,32s Many pregnant people face punitive consequences should they seek healthcare while pregnant, which could range from poor care to mistreatment to being reported to law enforcement or child welfare services.^9,34s Thus, the (real or perceived) risks of accessing prenatal care may be too high for some pregnant people.

Improving access to prenatal care requires new partnerships, programs, care models and policies.^35s First, while pregnant people with syphilis may not access prenatal care, they may access other community and social services. In case interviews with pregnant people with syphilis, Oregon LPHA staff have started collecting information on utilization of services like special supplemental nutrition program for women, infants and children (WIC), food banks, shelters, peer support services, substance use disorder treatment, mental health care, visiting nurse programs (universally offered in Oregon), street medicine programs, intimate partner violence resources, and anti-poverty programs (e.g., supplemental nutritional assistance program [SNAP], temporary assistance for needy families [TANF], and housing vouchers). Partnerships with these programs and resources could be leveraged not only for CS prevention but also for prenatal care engagement and persistence to improve outcomes among infants and pregnant people. OHA has additionally developed 340B partnerships with local jails and the Oregon Department of Corrections to increase STI screening in correctional settings. We recently issued recommendations to healthcare providers on best practices for preventing CS with the Oregon Perinatal Collaborative,^36s part of the National Network of Perinatal Quality Collaboratives.^37s To further support providers in screening for syphilis during pregnancy and to implement Oregon’s universal syphilis screening recommendation, we are also working with a non-profit organization that tailors electronic medical record systems for federally qualified health centers and public health clinics to create best practice alerts. In partnership with the Oregon Public Health Accountability Board, we developed public health metrics to track the work of state and local public health in reducing CS with a goal of encouraging Oregon Medicaid to adopt metrics and incentives for syphilis screening in pregnancy.

Second, innovative programs like the Abundant Birth Project,^38s which provides Black and Pacific Islander pregnant people in five California counties with an unconditional monthly income supplement to address racial and economic disparities in outcomes of pregnant people and infants, may also prevent CS. Third, we must restructure care provision for pregnant people. Low-barrier, trauma-informed, anti-racist prenatal care models that are mobile or drop-in, and co-located with trusted, community-based supportive services may improve access to care and prevent morbidity among pregnant people and infants, including syphilis and CS.^39s

Finally, all policy is health policy.^40s Policies addressing systemic racism, housing instability, poverty, violence, mass incarceration, substance use, mental health, and childhood trauma will impact rates of CS.

This work is subject to several limitations. First, there was significant missingness for potentially important predictors among pregnant people with syphilis in our surveillance data, and that missingness varied by whether the pregnant person was associated with a case of CS due more complete public health follow-up. In addition, prenatal care variables were only available for those who were associated with a case of CS. Second, surveillance data are not medical records data so we cannot assess why a pregnant person may have not received prenatal care, was not screened in the early third trimester, or did not receive adequate treatment. In addition, we cannot always know the care context of syphilis diagnosis and some pregnant people with syphilis may receive testing and treatment outside of prenatal care. Third, the county-level variables reflected different time frames during the study period based on the availability of data at the time of analysis and the associations of the county-level variables with CS risk may not be constant over time. While a smaller geographic area (e.g., census tract, zip code) may be more appropriate with respect to exposure to area-level disadvantage and its impact on health outcomes, there would be very few observations per area limiting the potential for robust statistical analysis. In addition, creating a score from a PCA does not allow for the evaluation of interactions between the county-level variables. Finally, these data represent a single state experience and may not generalize to other jurisdictions.

Injection drug use, corrections involvement, and greater county-level socioenvironmental challenges increased the risk of being associated with a case of CS among pregnant people with syphilis in Oregon. New partnerships, programs, care models, and policies are urgently needed to address the crisis of CS at local, state, and national levels.