Testing to Reduce Congenital Syphilis

Congenital syphilis is on the rise across the U.S. and in Texas, with serious health consequences for babies. In mothers, symptoms of syphilis can go unnoticed. But with timely prenatal care, routine maternal testing for the disease and appropriate treatment, congenital syphilis can be prevented and poor health outcomes mitigated.

Syphilis is a bacterial sexually transmitted disease that is most transmissible in the earliest stages, known as primary and secondary (P&S) syphilis, when a pregnant person may be unaware of having it and symptoms can go unnoticed.

Syphilis is treatable with antibiotics at all stages, including primary, secondary, early latent, late latent and tertiary.

A pregnant person with syphilis can transmit it to the baby during pregnancy or at delivery, at which time the baby contracts congenital syphilis (CS). CS can cause birth defects, miscarriage, preterm birth and stillbirth. Symptoms in the baby may not be present at birth.

Pregnant individuals with symptomatic syphilis have an 80 percent chance of having their pregnancy result in stillbirth or neonatal death, or of their infants at birth having signs and symptoms of syphilis.
Pregnant individuals with asymptomatic syphilis that is untreated or inadequately treated have a 23 percent chance of those outcomes.

Congenital syphilis is preventable if maternal infection is identified and treated in a timely manner. Long-acting benzathine penicillin G therapy is the only regimen approved by the Centers for Disease Control and Prevention (CDC) to treat syphilis during pregnancy to prevent transmission to the infant.

Benzathine penicillin G therapy has a success rate of up to 98 percent.
Length of treatment depends on the stage of syphilis, which the health-care provider determines.

Treatment must start as early as possible, and treatment helps the fetus as well. Treatment also is indicated for sexual partners.

The Law About Testing for Syphilis During Pregnancy

Texas law requires syphilis testing at three points during pregnancy, regardless of the mother’s risk factors, through routine blood testing.

First prenatal care visit
During the third trimester (no sooner than 28 weeks of gestation)
At delivery

Patient: Renata

Renata is 32 weeks pregnant when she presents for her first prenatal visit. She hasn’t been tested for syphilis yet, which would have occurred at a first prenatal visit scheduled soon after Renata was aware of the pregnancy. Now is another required time for testing — during the third trimester of her pregnancy, no sooner than 28 weeks. Two scenarios may result from the syphilis test:

Renata’s syphilis test is negative, so no action is needed. She will have another test at the time of delivery, which is required.

Renata’s syphilis test is positive. Her healthcare provider assesses the stage of her disease and prescribes a benzathine penicillin G regimen, a single injection for primary, secondary and early latent syphilis, or three doses at weekly intervals for late latent or latent syphilis of unknown duration (CDC, 2023). If Renata is at high risk for reinfection or lives in a geographic area with a high prevalence of syphilis, her healthcare practitioner will provide close serologic follow-up until the time of delivery. The risk of syphilis transmission to Renata’s baby is minimal if she receives proper antibiotic treatment.

Congenital Syphilis and the Baby

The risk for congenital syphilis infection is highest when the mother has P&S syphilis.
The risk of in-utero acquisition of syphilis is higher in babies of individuals who become newly infected with syphilis during pregnancy than in babies of individuals with unrecognized, untreated syphilis who then become pregnant.

Treatment for CS should be initiated at birth, regardless of symptoms, to prevent serious health problems from developing months or even years later.

Most patients deliver before their serologic response to treatment can be fully assessed, so postpartum follow-up of mother and newborn is critical. The CDC recommends clinical and serologic reassessment of mothers every 3 to 6 months for 12 to 24 months following treatment.

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References

Centers for Disease Control and Prevention. (2021). Sexually Transmitted Infections Treatment Guidelines, 2021 — Syphilis.