Syphilis During Pregnancy: Causes, Symptoms And Treatment

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Syphilis is a sexually transmitted disease that may occur due to unprotected sex with an infected partner. Syphilis in pregnancy may lead to vertical transmission to the fetus. Further, two of five babies born to mothers with a syphilis infection may experience fatal complications. Therefore, syphilis in pregnancy must be treated promptly with penicillin, which is the drug of choice for treating syphilis in pregnancy (1).

Read on to learn about the symptoms, complications, diagnosis, treatment, and prevention of syphilis during pregnancy.

Causes And Risk Factors For Syphilis In Pregnancy

The bacterium Treponema pallidum causes maternal syphilis and can be contracted through direct contact with syphilis sore in the mouth, penis, vagina, or anus during sex. A pregnant woman may transfer her infection to the infant during pregnancy or vaginal delivery through contact with syphilis sores (congenital syphilis), leading to adverse outcomes (1) (2) (3).

The risk factors for contracting syphilis in pregnancy are (4)

  • Having multiple sexual partners
  • Drug use, which may be associated with transactional sexual favors
  • Unstable housing or homelessness, which may compel women to receive housing or other support for sexual favors

Signs And Symptoms Of Syphilis During Pregnancy

According to the Centers for Disease Control And Prevention (CDC), a syphilis infection is followed by an asymptomatic incubation period of one to three months (5). During this time, the infection may present visible or dormant signs depending on the treatment undertaken. If left untreated, the infection may persist without visible signs.

The symptoms of syphilis in pregnancy differ depending on the stage of the infection (4).

Primary syphilis might manifest through a chancre, a hard and painless sore in the vagina.

Secondary syphilis may present some of these symptoms a few days after contracting the infection:

  • Rashes in the palms and feet
  • Fever
  • Lymph infection
  • Headache
  • Hair loss
  • Weight loss
  • Muscle ache
  • Fatigue

Latent syphilis may not show any visible signs and symptoms,  although the infection lingers in the body and may cause adverse outcomes.

Late or tertiary syphilis may have progressive symptoms. It might affect several vital organs and create complications if left untreated.

Complications Of Syphilis Infection During Pregnancy

Complications affecting the outcome of pregnancy

Pregnant women with syphilis may infect their unborn babies through vertical transmission, leading to some of the following complications that affect pregnancy outcomes (1) (4).

  • Stillbirth or neonatal death: Untreated infections in pregnant women lead to fetal death in almost 40% of cases.
  • Preterm delivery: Women undergoing syphilis treatment have a high risk of premature labor.
  • Low birth weight: The fetus might have reduced growth and weigh less than five pounds and eight ounces.
  • Placenta and umbilical cord issues: The placenta and umbilical cord may become swollen, affecting the oxygen supply to the fetus.

Complications for the baby

The risk of syphilis infection to the growing fetus depends on the stage of maternal syphilis infection during pregnancy. According to the CDC, the highest fetal infection rate is during the primary and secondary stages.

Untreated syphilis and fetal transmission can cause severe complications for the baby later in life, including (1) (4) (6) 

Bone damage

  • Severe anemia
  • Enlarged liver and spleen
  • Jaundice
  • Meningitis
  • Skin rashes
  • Vision problems, including blindness
  • Cardiac complications
  • Neurological complications such as seizures, movement disorders
  • Muscle problems
  • Lifelong health issues

Diagnosis Of Syphilis During Pregnancy

The CDC guidelines mandate screening for syphilis in the first prenatal care visit and twice in the third trimester (4). Syphilis can be diagnosed using at least two serological methods (5).

  • Direct testing involves the identification of the causative bacteria using darkfield microscopy or finding genetic traces of the bacteria using polymerase chain reaction (PCR). However, these tests are unpopular due to the unavailability of sophisticated instruments and skilled personnel.
  • Serological tests use antibodies to find the causative organism in the body and are more widely used due to the ready availability of reagents and instruments.
  • A non-treponemal test involves finding dead bacteria or its fragments using specific antibodies.
  • Treponemal antibody testing identifies the bacterial protein using specific antibodies. However, such positive tests may require another non-treponemal test to identify the infection quantitatively and determine the treatment regime.

Treatment For Syphilis During Pregnancy

Syphilis in pregnant women is usually treated with penicillin (2). According to the CDC, the dosage depends on the level of bacterial load in the body and the stage of infection (4). The entire course of the antibiotic must be completed even if no symptoms are visible.

If syphilis is diagnosed in the second half of pregnancy, fetal sonographic evaluation and prenatal syphilis screening are conducted to understand the risk of congenital syphilis and fetal distress. In this case, the second dose of antibiotic is prescribed as an effective treatment to reduce the risk of perinatal death. A doctor will conduct a blood test after the treatment to confirm if you are free of the infection.

If diagnosed with syphilis, abstain from further sexual conduct until a doctor declares it safe, and inform any sex partners from the past two years as they might have it as well. Following the treatment, safe sex is recommended as it is possible to contract the infection again. Conducting the diagnostic tests at regular intervals is also a good practice.

Prevention Of Syphilis In Pregnancy

Syphilis can be prevented in pregnancy by adhering to some of the following measures (1) (3):

  • Use latex condoms during sex.
  • Adhere to a monogamous relationship with a partner who has been tested.
  • Attend all the prenatal care checkups and do the serological tests despite showing no visible symptoms of syphilis infection.

Syphilis is a contagious but preventable disease. Pregnant women with syphilis may transfer the infection to the growing fetus, causing serious complications. Understanding the symptoms, complications, and treatment plan can help in getting optimal protection against the disease. If you note the development of any syphilis symptoms, consult your healthcare provider and get tested.


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Dr. Lakshmi Chirumamilla

Dr. Lakshmi Chirumamilla is a consultant at Nova IVF Fertility Clinics, Hyderabad. She has experience in core cases of infertility including poor ovarian response, recurrent implantation failure, and male factor infertility. With her expertise and experience, she has cracked complex cases and is known to provide the best patient care. Working since August, 2014 at Nova, she handled international patients... more

Anshuman Mohapatra

Anshuman Mohapatra is a biotechnology scientist with more than six years of research experience in analytical chemistry and biotechnology. He has submitted his Ph.D thesis at the Indian Institute of Technology Guwahati (IIT Guwahati) and served as a research fellow (JRF/SRF) during his Ph.D tenure. His research interest includes analytical chemistry, neurobiology and lipid disorder diseases. Three of his research... more