Pregnant Women With Syphilis, Substance Use More Likely to Pass Infection to Babies

Pregnant patients with syphilis who used substances had a greater chance of passing the infection along to their baby compared with those without substance use, according to a CDC study conducted in Arizona and Georgia.

From 2018 to 2021, patients who had a congenital syphilis pregnancy outcome -- defined as a syphilitic stillbirth or a live birth with a syphilis diagnosis -- had almost double the rate of substance use compared with those without this outcome (48.1% vs 24.6%; prevalence ratio [PR] 1.95, 95% CI 1.60-2.38), reported Jeffrey Carlson, PhD, of Eagle Global Scientific in Atlanta, and colleagues.

Those with a congenital syphilis pregnancy outcome were also more likely to report illicit opioid use (20.8% vs 3.4%; PR 6.09, 95% CI 3.50-10.58), and more likely to have used illicit non-prescription drugs (28.1% vs 6.4%; PR 4.41, 95% CI 2.94-6.63), the researchers noted in the Morbidity and Mortality Weekly Report.

Of note, among the patients with these outcomes, 53% who used substances and 32% of those who did not received prenatal care starting only in the third trimester, or not at all. For those with a non-congenital syphilis pregnancy outcome, these percentages were 17% and 6%, respectively.

Carlson and colleagues emphasized the need for prompt diagnosis and treatment of the infection to reduce poor outcomes. "Although syphilis is highly treatable with penicillin G, one-third of persons in this analysis who used any substances remained untreated," they wrote.

Fifteen percent of patients with a congenital syphilis pregnancy outcome received adequate treatment, the team noted.

Irrespective of pregnancy outcomes, 40% of patients with substance use received late or no prenatal care compared with 16% of those who did not have substance use. Patients with substance use had an average of six prenatal care visits, while those without substance use had nine.

"Although screening and treatment can prevent most cases of congenital syphilis, numerous barriers to implementing these prevention strategies exist, some of which might be amplified among persons who use substances," they concluded. "Tailored interventions need to address barriers and facilitators for accessing screening and treatment for syphilis for persons with current or previous substance use, including those with a history of incarceration and homelessness."

Despite universal prenatal syphilis screening and the wide availability of effective antibiotics, the incidence of congenital syphilis in the U.S. has been on the rise. At the same time, data have shown increases in methamphetamine, injection drug, and heroin use in women with syphilis, Carlson's group noted.

In this analysis, the researchers compared the prevalence of substance use in patients with and without congenital and non-congenital syphilis, using data from the Surveillance for Emerging Threats to Pregnant People and Infants Network (SET-NET), a longitudinal surveillance study monitoring infectious diseases among pregnant patients and their infants. They analyzed births that occurred from 2018 to 2021 in Arizona and Georgia.

Substance use included the use of tobacco, alcohol, cannabis, illicit opioids, or other illicit non-prescription drugs.

Overall, 770 pregnant patients with syphilis were included in the analysis, nearly half of whom had a congenital syphilis pregnancy outcome.

Of all patients who used substances, 16% of those with a congenital syphilis pregnancy outcome and 11% of those with a non-congenital outcome had a history of incarceration. Additionally, 27% and 9%, respectively, had a history of homelessness at some point within the previous year.

Carlson and colleagues described a few limitations to their research, including that data collection is ongoing and only from two states. They also noted that substance use prevalence likely differs by jurisdiction, so these results may not be generalizable. Additionally, stigma and social desirability bias may lead to underreporting of substance use. Data describing incarceration and homelessness in this population were missing for 39% and 35% of people included in this analysis, they added.

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