Symptom guide · Pregnancy Smart
Syphilis during pregnancy
By trimester
Weeks 1–13
1st trimester
Syphilis screening belongs at the first prenatal visit, even after a prior negative test. A reactive screen needs confirmatory testing, stage assessment, and prompt penicillin planning rather than waiting for a sore or rash.
Weeks 14–27
2nd trimester
Syphilis identified in the second half of pregnancy may prompt fetal ultrasound, but imaging should not delay penicillin. Fever, contractions, or reduced fetal movement after a dose need obstetric attention because a Jarisch-Herxheimer reaction can affect the pregnancy.
Weeks 28–birth
3rd trimester
ACOG advises universal rescreening in the third trimester and again at birth. The delivery team needs the maternal test history, stage-appropriate penicillin record, follow-up titers, and reinfection assessment to plan newborn evaluation.
What does the evidence show for syphilis?
- ACOG's 2024 practice advisory recommends syphilis screening for every pregnant patient at the first prenatal visit, in the third trimester, and at birth rather than limiting repeat tests to risk-based groups. 1
- CDC identifies penicillin G as the only antimicrobial known to address fetal infection and congenital syphilis risk, with the regimen selected according to the maternal stage of infection. 2
- When a pregnant patient has a penicillin allergy, CDC advises allergy evaluation when appropriate, desensitization, and penicillin because no proven alternative regimen is available for pregnancy. 3
- Congenital syphilis can be present without signs at birth, and infant decisions use the maternal infection history, adequacy and timing of penicillin, infant examination, and paired nontreponemal titers. 4
- Syphilis can pass during pregnancy and is associated with miscarriage, stillbirth, prematurity, low birth weight, newborn death, and later neurologic or sensory problems when congenital infection is not addressed. 5
When should I call my provider about syphilis?
Contact obstetric care immediately for fever, contractions, or decreased fetal movement after penicillin because a Jarisch-Herxheimer reaction can affect the pregnancy. Do not wait for symptoms after a reactive test or known exposure, and seek urgent assessment for vision loss, new hearing loss, severe headache, confusion, weakness, or other neurologic changes. Whatever the pattern, any symptom that feels beyond your usual range is a reason to call: obstetric teams expect these questions and would rather hear early than late.
Frequently asked questions
Can syphilis during pregnancy have no symptoms?
Yes. Syphilis during pregnancy can cause no symptoms, mild symptoms, or findings that resemble another illness. A blood test is therefore important even when there is no sore, rash, fever, or known exposure.
When is syphilis screening done during pregnancy?
Current ACOG guidance calls for syphilis screening at the first prenatal visit, universal rescreening in the third trimester, and another test at birth. State requirements may add timing details, but a missed early visit should not mean a missed test.
What happens after a reactive syphilis screening test?
A reactive syphilis screen is interpreted with a quantitative nontreponemal test and a confirmatory treponemal test when results conflict. Prior records, antibody titers, symptoms, and exposure history help distinguish current infection, past adequate care, reinfection, and a false-positive screen.
Which penicillin regimen is used for syphilis in pregnancy?
The penicillin regimen depends on syphilis stage. Early and later latent infections use different schedules, so a clinician must establish the stage and check prior records. Missed intervals in a weekly late-latent series can require restarting the full series.
What if I am allergic to penicillin?
A penicillin-allergy label does not create a proven substitute for syphilis during pregnancy. CDC advises specialist allergy evaluation when useful, followed by desensitization and penicillin for those with confirmed or likely allergy. This should occur in a monitored clinical setting.
Do sexual partners need care after syphilis is found in pregnancy?
Yes. Sexual partners need evaluation, testing, and stage-appropriate medication so they receive care and do not pass syphilis back. Avoid sexual contact until the clinical team says both partners have completed the necessary steps.
Why are syphilis titers repeated after penicillin?
Quantitative nontreponemal titers help clinicians assess response and possible reinfection. A fourfold decrease may not occur before birth and does not automatically mean failure, while a sustained fourfold rise is concerning for reinfection or an inadequate response.
What is a Jarisch-Herxheimer reaction in pregnancy?
A Jarisch-Herxheimer reaction is an acute fever and inflammatory response that can occur after syphilis medication. During the second half of pregnancy, fever, contractions, or decreased fetal movement after a dose should prompt immediate obstetric contact, but concern about the reaction should not delay necessary penicillin.
How is a baby evaluated after syphilis during pregnancy?
Newborn evaluation depends on the maternal stage, penicillin regimen and timing, evidence of reinfection, the infant examination, and comparison of maternal and infant nontreponemal titers. Some infants also need blood counts, spinal-fluid testing, long-bone imaging, penicillin, and serial follow-up.
Related in the library
References
Screening for Syphilis in Pregnancy
ACOG · https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2024/04/screening-for-syphilis-in-pregnancy
Syphilis During Pregnancy - STI Treatment Guidelines
CDC · https://www.cdc.gov/std/treatment-guidelines/syphilis-pregnancy.htm
Managing Persons Who Have a History of Penicillin Allergy
CDC · https://www.cdc.gov/std/treatment-guidelines/penicillin-allergy.htm
Congenital Syphilis - STI Treatment Guidelines
CDC · https://www.cdc.gov/std/treatment-guidelines/congenital-syphilis.htm
CDC · https://www.cdc.gov/syphilis/about/about-congenital-syphilis.html
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