Syphilis is a sexually transmitted disease that enters the fetus during pregnancy and leads to congenital syphilis. It is linked with premature birth, stillbirth, low birth weight, major infant abnormalities, and neonatal death. The US has reported 3882 cases of congenital syphilis in 2023. The new syphilis case rates have increased over the last 3 decades, specifically in females. Syphilis rates are 2 to 4 times higher in females than in males from 2017 to 2023. Congenital syphilis cases increased by more than 10-fold over the past decade. About 90 % of the new congenital syphilis cases can be prevented with early screening and proper treatment.
The US Preventive Services Task Force (USPSTF) has modified its 2018 guidelines to test syphilis infection in pregnant females. The reaffirmation method is used for evidence-based standards in the primary care practice. The USPSTF concluded that screening for syphilis infection in pregnant females has a significant net benefit. Previous studies have found that there are fewer adverse pregnancy effects among pregnant females who were screened and treated for syphilis infection in comparison with those who were untreated. Early treatment is more helpful during pregnancy. A 2014 systematic review of 54 observational studies found that the rates of congenital syphilis, low birth weight, preterm birth, stillbirth, and neonatal deaths were significantly reduced in pregnant females who were treated for syphilis during pregnancy.
Syphilis is a very serious infection that affects all pregnant females irrespective of risk factors. Screening test for syphilis includes blood tests that detect antibodies produced in response to Treponema pallidum infection. The treponemal test can detect an antibody specific to the T. pallidum antigen. Nontreponemal tests can detect antibodies that can damage the tissue from T. pallidum infection or any other condition that can release the lipoidal antigens. This 2-step testing can improve the diagnostic accuracy, specifically in high false-positive results linked with the nontreponemal test alone in pregnancy.
A point-of-care test for T. pallidum antibody is available, which can be conducted at home or in clinics by using a fingerstick blood sample and does not need laboratory processing. It is recommended to do the confirmatory tests to diagnose it accurately. All pregnant females must be tested for syphilis as early as possible during prenatal care. It is not done in the early stage; it must be conducted at the 1st opportunity. Some studies suggest that 25 to 50% of the congenital syphilis cases can be prevented by repeated screening in the 3rd trimester of pregnancy.
The Centers for Disease Control and Prevention (CDC) recommends parenteral penicillin G be the only treatment with proven efficacy during pregnancy. Each stage of the syphilis disease has a specific treatment protocol. Long treatment duration is necessary for the later-stage infection. In the second trimester of pregnancy, a female is diagnosed with syphilis; sonographic evaluation of the fetus is recommended to assess for the symptoms of congenital syphilis. Females who are sensitive to penicillin treatment should be desensitized and then treated with penicillin.
The USPSTF has suggested routine screening for syphilis in adolescents and adults and other sexually transmitted infections like gonorrhea, chlamydia, hepatitis B virus, HIV, and genital herpes. It recommends counseling to prevent these infections. The 2018 reaffirmation recommendation indicated that screening for syphilis during pregnancy surpassed the risks, and no additional substantial data could change this. Therefore, the USPSTF reaffirms its recommendation to test for syphilis during pregnancy.
Reference: US Preventive Services Task Force. Screening for Syphilis Infection During Pregnancy: US Preventive Services Task Force Reaffirmation Recommendation Statement. JAMA. Published online May 13, 2025. doi:10.1001/jama.2025.5009
