What is the recommended treatment for syphilis in pregnant women?

Treatment of Syphilis During Pregnancy

Penicillin G benzathine is the only proven effective treatment for syphilis during pregnancy, with dosing based on the stage of maternal infection. 1

Recommended Treatment Regimens

Primary, Secondary, or Early Latent Syphilis (<1 year duration)

• Standard regimen: Benzathine penicillin G 2.4 million units IM in a single dose 2, 1
• Some experts recommend a second dose of 2.4 million units IM one week after the initial dose, especially for:
  • Women in the third trimester
  • Women with secondary syphilis
  • HIV-infected pregnant women
  • Areas with high syphilis prevalence 1, 3

Late Latent Syphilis (>1 year or unknown duration)

• Benzathine penicillin G 2.4 million units IM weekly for 3 consecutive weeks (total 7.2 million units) 2, 1
• Treatment completion rates for the full 3-dose regimen are often suboptimal (42.9% in general population, 68.7% in pregnant women) 4

Neurosyphilis

• Patients with CSF findings consistent with neurosyphilis should be treated according to neurosyphilis protocols 2

Special Considerations

Penicillin Allergy

• Pregnant women with penicillin allergy must undergo desensitization followed by penicillin treatment 2, 1
• Alternative antibiotics are not recommended:
  • Tetracyclines are contraindicated during pregnancy (cause fetal bone/teeth staining)
  • Erythromycin does not reliably treat fetal infection
  • Insufficient data exists for azithromycin or ceftriaxone use in pregnancy 2, 1
• Oral desensitization protocols have been successfully implemented with good safety profiles 5

Jarisch-Herxheimer Reaction

• Occurs in up to 44% of treated pregnant women 6
• Can cause uterine contractions, fetal heart rate abnormalities, and rarely stillbirth
• For viable pregnancies, consider administering the first dose in a labor and delivery setting with continuous fetal monitoring for 24 hours 6
• Women should be advised to seek immediate obstetric attention if they notice contractions or decreased fetal movement 2

HIV Co-infection

• All pregnant women with syphilis should be tested for HIV 2, 1
• HIV-infected pregnant women may benefit from a second dose of benzathine penicillin G one week after the initial dose 2

Screening and Follow-up

• All pregnant women should be screened at first prenatal visit 2, 1
• High-risk women or those in high-prevalence areas should be screened again at:
  • 28 weeks gestation
  • Delivery 2, 1
• Serologic titers should be repeated in the third trimester and at delivery 2
• Monthly monitoring is recommended for women at high risk of reinfection 2

Ultrasound Considerations

• Fetal ultrasound is recommended when feasible in pregnancies >20 weeks 6
• Common ultrasound findings include:
  • Hepatomegaly
  • Placentomegaly
  • Elevated middle cerebral artery peak systolic velocity
  • Ascites
  • Hydrops fetalis 6
• Pregnancies with ultrasound abnormalities are at higher risk of complications during treatment and fetal treatment failure 6

Treatment Efficacy

• CDC-recommended regimens have shown 98.2% success rate in preventing congenital syphilis 7
• Secondary syphilis during pregnancy carries the highest risk of fetal treatment failure 7
• Treatment should never be delayed due to concerns about complications 1

By following these evidence-based guidelines, maternal-fetal transmission of syphilis can be effectively prevented in the vast majority of cases, significantly reducing the risk of congenital syphilis and its devastating consequences.