Treatment of Syphilis in Pregnant Women
Penicillin G is the only recommended treatment for syphilis during pregnancy, as it is the only proven effective medication to prevent mother-to-fetal transmission. 1
First-Line Treatment Regimens
- For primary, secondary, or early latent syphilis: Penicillin G benzathine 2.4 million units IM in a single dose, with some specialists recommending a second dose one week later, especially in the third trimester 1
- For late latent syphilis or syphilis of unknown duration: Penicillin G benzathine 7.2 million units total, administered as 3 doses of 2.4 million units IM each at one-week intervals 1
Special Considerations
- There are no proven alternatives to penicillin for treating syphilis during pregnancy 1
- Women with penicillin allergies should undergo desensitization and then be treated with penicillin rather than using alternative antibiotics 1
- Tetracycline, doxycycline, and erythromycin are contraindicated during pregnancy 1, 2
- Erythromycin should not be used as it does not reliably cure fetal infection 1, 3
- Untreated syphilis in pregnancy results in approximately 40% pregnancy loss (spontaneous abortion, stillbirth, or perinatal death), 40% congenital syphilis, and only 20% healthy infants 4
Follow-Up Recommendations
- Serologic titers should be repeated in the third trimester and at delivery 1
- Monthly serologic testing is recommended for women at high risk of reinfection or in areas with high syphilis prevalence 1
- No newborn should be discharged from the hospital without determining maternal serologic status at least once during pregnancy 1
Prevention of Congenital Syphilis
- All pregnant women should undergo serologic testing for syphilis at the start of pregnancy 1
- In high-risk populations, testing should be performed twice during the third trimester and at delivery 1
- Sexual partners of women diagnosed with syphilis during pregnancy should be evaluated and treated 1
- For partners of women with primary, secondary, or early latent syphilis, presumptive treatment is recommended even if seronegative if exposure occurred within 90 days 1
Common Pitfalls to Avoid
- Inadequate treatment regimens: Using non-penicillin antibiotics that don't cross the placenta effectively can result in fetal infection despite maternal cure 3
- Delayed treatment: Treatment less than 4 weeks before delivery may not prevent congenital syphilis 5
- Inadequate follow-up: Failure to monitor serologic response to treatment may miss treatment failures or reinfection 1
- Penicillin alternatives: Despite good safety records of some antibiotics after accidental use, fluoroquinolones are contraindicated during pregnancy 3
Treatment of syphilis during pregnancy is critical to prevent the devastating consequences of congenital infection. The high rates of adverse pregnancy outcomes in untreated cases highlight the importance of proper screening, treatment, and follow-up care.