Identifying gaps in syphilis treatment and prenatal care among pregnant individuals


Preventing congenital syphilis comes down to quick diagnosis and treatment of the infection in pregnancy, and the number of missed opportunities to do so in the United States continues to grow.

illustration of microscopic syphilis bacterium| Image Credit: © Christoph Burgstedt / Adobe Stock

(Adobe Stock / Christoph Burgstedt)

The incidence of maternal syphilis in the United States is climbing at an alarming rate, with cases ballooning 222% from 2016 to 2022.1 This has resulted in a concurrent rise in congenital cases of syphilis, which carries significant risk, including neonatal morbidity and mortality. The key to prevention of congenital syphilis is diagnosis and treatment prior to pregnancy or, if diagnosed during pregnancy, treatment more than 30 days before the delivery date.

An analysis of enhanced surveillance data by investigators with the US Centers for Disease Control and Prevention (CDC) sought to uncover missed opportunities to prevent congenital infection by exploring both the factors that affect treatment and how prenatal care impacts outcomes for women diagnosed with syphilis during pregnancy. Their results were presented as a late-breaking abstract at the American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting in San Francisco, California, from May 17-19, 2024.2

Armed with data from 6 jurisdictions in the Surveillance for Emerging Threats to Pregnant People and Infants Network (SET-NET) program, investigators observed that timeliness of both prenatal care and syphilis treatment had the biggest impact on incidence of congenital infection. Additionally, there were ample missed opportunities for intervention, most commonly associated with either late treatment initiation or inadequate or no treatment for individuals with complicated social histories.

“You won't be surprised to learn that rates of congenital syphilis have increased right along rates among reproductive age women in the United States,” investigator Kate Miele, MD, MA, FACOG, with the US Centers for Disease Control and Prevention, told Contemporary OB/GYN in an interview. “In 2022, we had 3755 cases of congenital syphilis in the United States and, from my point of view, every single case of congenital syphilis is a failure of our public health system and our health care system.”

SET-NET linked investigators to multiple data sources, including vital records, electronic lab records, the National Notifiable Diseases Surveillance System, and medical records, including birth records and information obtained at child well-visits. Individuals with a pregnancy outcome between 2018 and 2021 who met the surveillance definition for syphilis during pregnancy were included in the study, as well as those who had a stillborn or liveborn with congenital syphilis.

Some of the key variables examined included stage of syphilis and corresponding treatment. Primary, secondary, and early latent syphilis (P/S/E) were treated with 1 shot of benzathine penicillin G, while late latent syphilis and latent syphilis of unknown duration (LL/U) were treated with 3 shots of benzathine penicillin G.

Investigators also looked at timeliness of prenatal care and split it up into 3 groupings. Timely prenatal care (PNC) was defined as care initiated at least 30 days before the pregnancy outcome, which is considered early enough to treat congenital syphilis. Non-timely prenatal care was defined as care initiated less than 30 days before the pregnancy outcome. Non-timely—as well as no—prenatal care both resulted in not being able to prevent congenital syphilis.

Adequacy of syphilis treatment was also assessed. Investigators considered adequate treatment to mean that the individual received the correct medication at the correct dose base on stage of infection and initiated that treatment at least 30 days before the pregnancy outcome.

Of the 1477 cases included in the analysis, 602 individuals (41%) had P/S/E syphilis, while 875 (59%) had LL/U infection. A total of 856 individuals received adequate treatment (57.9%), while 621 (42.1%) received either inadequate treatment or not treatment at all. Of those with P/S/E infection, 358 (59%) received adequate treatment, 90 (15%) received inadequate treatment, and 154 (26%) received no treatment. A total of 498 individuals with LL/U syphilis (56%) received adequate treatment, 173 (19%) received inadequate treatment, and 204 (23%) received no treatment.

Inadequate treatment was more of a timing issue than anything else, Miele said. “In order to prevent congenital syphilis, treatment for syphilis during pregnancy must be initiated at least 30 days before the pregnancy outcome, and what that means is that if people do not present a prenatal care at least 30 days before their pregnancy outcome, we don't have enough time to screen and treat for syphilis.”

Indeed, for 98% of those in the P/S/E group who received inadequate treatment, it is because the treatment was initiated < 30 days from the pregnancy outcome. The factors were a bit more complicated for those with LL/U syphilis. Of those who received inadequate treatment, 62% received too few doses, 46% had doses that were administered too far apart, 43% initiated treatment < 30 days from the pregnant outcome, 26% received doses that were administered too close together, and 4% received the wrong medication.

Investigators also observed that social determinants of health and access to care influence treatment. Individuals experiencing substance use and homelessness were 33% and 20% more likely to receive inadequate or no treatment, respectively. These populations, along with those who are incarcerated, are at a heightened risk of not receiving the proper treatment. This underscores the need for custom approaches to screen, diagnose, and treat syphilis during pregnancy for these people.

Timely PNC generally led to adequate treatment; however, notably, 32% of those who received timely PNC received either inadequate or no treatment. Importantly, timely PNC is not the only way to receive adequate treatment for syphilis, as 12% of those who received no PNC and 20% of those with non-timely PNC were still able to receive adequate treatment.

Overall, the data illuminate gaps in prenatal care that can serve as barriers to adequate treatment for syphilis, Miele said. “Syphilis is hard, and I know that and everyone who takes care of patients within our community knows that. Although timely prenatal care remains an important opportunity for getting people syphilis care, we need to be looking at other opportunities to reach people.”


  1. Gregory CEW, Ely DM. Trends and characteristics in maternal syphilis rates during pregnancy: United States, 2016–2022. NCHS Data Brief No. 496. Published February 2024. Accessed May 16, 2024.,The%20rate%20of%20maternal%20syphilis%20increased%20from%202016%20through%202022,100%2C000%20births%20(Figure%201).
  2. Syphilis treatment among people who are pregnant in six U.S states, 2018–202. Presented at: The American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting. San Francisco, CA. May 17-19, 2024.
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