Syphilis in Pregnancy: What You Need to Know

Medically reviewed on July 19, 2023 by Amy Harris, MS, RN, CNM. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

• Congenital Syphilis on the Rise in the United States
• What Are the Risk Factors for Having Syphilis in Pregnancy?
• How Is Maternal Syphilis Transmitted in Pregnancy?
• Timing Matters For How Syphilis Affects Pregnancy
• What Are the Effects of Syphilis in Pregnancy?
• Early and Late Congenital Syphilis
• Is Treatment Available for Congenital Syphilis?
• How Is Syphilis Diagnosed in Pregnancy?
• How to Reduce the Spread of Syphilis and Prevent Congenital Syphilis
• Hone in on Your Health with Everlywell
• Related Content

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. Mothers infected with syphilis can pass the bacterial infection during pregnancy or childbirth to their babies. This is called congenital syphilis. If not treated, syphilis infections can cause serious health consequences for both mother and child. The tragedy is that all cases of congenital syphilis are entirely preventable – syphilis can be cured easily in both mother and baby with the antibiotic penicillin, as long as the infection is caught early. [1]

Congenital Syphilis on the Rise in the United States

In 2021, there were at least 77.9 cases of congenital syphilis per 100,000 live births, marking a 30.5 percent increase in fetal infections since 2020. And, even more shockingly, is a reported 219.3% increase in congenital syphilis cases between 2017 and 2020. [2]

Why such a dramatic and tragic increase? Congenital syphilis was once so rare that it was considered to be “on the verge of elimination.”4 Public health researchers and healthcare providers have several theories why congenital syphilis is rebounding. First, recent syphilis outbreaks have been concentrated in certain populations and parts of the country. Syphilis is more common in the southern states of the United States, in substance-using populations, people who they themselves or their partners are incarcerated, those engaged in sex work, or those with unstable housing or houselessness. [2,3]

Widening health disparities along racial and socio-economic lines, intensified by the COVID-19 pandemic may explain some of the recent rises in congenital syphilis. Uneven access to prenatal care among women of different races and ethnicities is another explanation for differences in congenital syphilis rates across racial and socio-economic lines. Finally, decreased funding and staffing cuts in public health services and STI clinics have left high-risk groups without access to life-saving care.

What Are the Risk Factors for Having Syphilis in Pregnancy?

The US Centers for Disease Control (CDC) reports that people with syphilis during pregnancy or infants born with congenital syphilis are more likely to report [3]:

• Sex with multiple partners
• Sex in conjunction with drug use or transactional sex
• Late entry to prenatal care (i.e., first visit during the second trimester or later) or no prenatal care
• Methamphetamine or heroin use
• Incarceration of the pregnant person or their partner; or
• Unstable housing or homelessness

Syphilis can be hard to recognize and diagnose because there are four stages of syphilis (primary, secondary, latent, and tertiary), with different symptoms that can happen over weeks, months, and years. [3] The signs and symptoms of syphilis in females are the same whether she is pregnant or not [4]

In the first stage, called primary syphilis, you may or may not notice a round, painless sore, or chancre, usually on the genitals, around the anus, in the mouth, or possibly on the eyelid. [5] Those with the infectious disease may experience a skin rash, fatigue and fever, joint and muscle pain, hair loss, and/or malaise. Syphilis is sometimes called the great pretender with these symptoms, it mimics so many other common conditions (cold, flu, COVID-19, Lyme disease, just to name a few). With all of the changes in your body with pregnancy, it might be easy to miss signs of syphilis or attribute them to pregnancy instead. [3,6]

Other people will not have any symptoms or symptoms will be mild enough that they don’t notice them.It can take anywhere from 10 to 90 days to develop symptoms of primary syphilis once infected, but most people develop symptoms around 3 weeks (21 days). [3] Without treatment, the infection passes through the series of four stages. It may be dormant in your body for years or even decades (the latent phase without any symptoms), before returning aggressively in the tertiary stage to attack your brain, nerves, eyes and other organs. Untreated, syphilis can lead to deafness, blindness or death. [5]

If not treated, a pregnant woman can infect sexual partners through vaginal, oral, or anal sex. It is possible to get syphilis without having sex, most commonly through skin-to-skin contact with the chancre and partners’ mouths or genitals. [3]

How Is Maternal Syphilis Transmitted in Pregnancy?

A pregnant mother with syphilis can transmit the syphilis bacterium to her child through the blood that flows from her body, through the placenta and umbilical cord, to the fetus. Infection can also occur through direct contact with an infected chancre or sore during childbirth. [4]

That said, once infected, the symptoms of the infectious disease can take a few weeks to show. [4]

Timing Matters For How Syphilis Affects Pregnancy

How a syphilis infection impacts the fetus’s or infant’s health depends on when the mother becomes infected with syphilis and if — or when — she receives treatment for the infection. Whether or not a baby becomes infected with syphilis depends on which stage of syphilis the mother has and how far along the pregnancy is when she becomes pregnant (called the gestational age). [7]

Babies born to mothers who acquire syphilis during the third trimester carry the greatest risk of developing congenital syphilis. There is a lower risk of transmission (and the baby getting infected) if the mother is in early or late latent stage syphilis and a higher risk of transmission (60-100 percent) if she is pregnant with either primary or secondary syphilis. [4]

The timing of treatment also matters. The earlier in pregnancy a woman receives treatment (at least prior to 4 months or 16 weeks gestational age), the more likely the mother and child will be cured of the infection. [4]

What Are the Effects of Syphilis in Pregnancy?

When pregnant women are infected with syphilis, estrogen levels can decrease while progesterone levels increase to levels which can not support a healthy pregnancy. Fetal Infection with the Treponema pallidum bacteria sets off a toxic inflammatory hurricane for the developing fetus. Harmful infection and inflammation spreads to the placenta, amniotic fluid, fetal brain and spinal fluid, liver, and heart. [7] The placenta does not work as well, so the fetus does not receive enough blood to grow and fetal growth restriction and low birth weight result.

Changes in blood flow and inflammation of the placenta also cause blood disorders such as anemia, swelling and damage to the developing liver and spleen. [6] Reduced blood flow, inflammation, and infection of the fetal brain and spinal fluid result in brain damage, impaired cognitive ability if the baby survives pregnancy, seizures after birth, and early infant death. [7] Sometimes, if a pregnant person has access to prenatal care, these fetal changes caused by maternal syphilis infection can be picked up by ultrasound. Two frequently observed ultrasound signs of congenital syphilis are:

• Hydrops – Characterized by fluid build-up in the infant’s body cavities, typically in the abdominal cavity and/or chest. Swelling can also impact the baby’s eyes, leading to lateral corneal swelling, which can cause vision loss or eye pain.
• Hepatosplenomegaly – Seen as an enlargement of the liver or spleen on ultrasound.

These changes caused by bacterial infection threaten the health of the developing pregnancy and fetus. An estimated 50-80 percent of pregnant women with syphilis experience an adverse pregnancy outcome including stillbirth (baby born dead) or miscarriage if they do not receive prompt treatment for their syphilis infection (Tsai).

Early and Late Congenital Syphilis

The majority (70%) of babies born alive with syphilis do not have any signs or symptoms of disease. [4] Sadly, this can delay diagnosis and life-saving treatment. If not recognized at birth, infected newborns can have seizures, later developmental delays, and even die shortly after birth. [3] At birth, they may not yet have a positive syphilis blood test, because the disease can take weeks to show up on screening tests. For this reason, if you are considered high-risk for having syphilis, your baby needs to have blood tests done every few weeks after birth. The early signs of a syphilis infection in babies can include [4,5]:

• Deformed bones
• Low blood count
• Enlarged spleen and liver
• Yellowing of the skin or eyes (jaundice)
• Meningitis
• Skin rashes
• Blindness, glaucoma, or cataracts
• Deafness
• Rhinitis (snuffles)
• Fever
• High cholesterol levels
• Inflamed limbs and joints

Most symptoms of congenital syphilis begin to show within weeks (three to fourteen)—or years (two to five)—of life. [4]

If not treated, the infection can lead to further neurological damage (neurosyphilis) and eye damage (ocular syphilis). [5] Infants with congenital syphilis who are not treated within the first 3 months of life are more likely to have lifelong complications such as deafness, blindness, and intellectual disability. [4,7,11]

In some cases, latent congenital syphilis may not be diagnosed until much later in life, when the infection has had time to cause major health consequences such as [9]:

• Bone pain
• Retinitis pigmentosa (eye disease)
• Hutchinson’s triad (peg-shaped upper central teeth)
• Saddle nose
• Bony forehead
• High arched palate
• Short upper jawbone
• Nerve deafness
• Fissuring around the mouth and anus
• Interstitial keratitis (blurred vision, abnormal tearing, eye pain, and sensitivity to light)

Is Treatment Available for Congenital Syphilis?

Yes, treatment is available for congenital syphilis. Penicillin is the only antibiotic that can treat perinatal syphilis and cross the placenta at high enough levels to prevent or treat infection in the fetus. At this time, there are no proven alternatives to penicillin. [4]

Therefore the CDC advises healthcare providers to only use penicillin therapy to treat syphilis. Treatment with penicillin is extremely effective (success rate of 98%) in preventing transmission to the baby. Pregnant people who are allergic to penicillin should see a specialist for desensitization to penicillin. [3,10]

While the length of treatment depends on your syphilis stage and the severity of your infant’s infection, it’s most common to administer the antibiotic for 10 to 14 days. [10,13] Early identification and treatment of early-stage perinatal syphilis is 98% effective in preventing the mortality and morbidity associated with congenital infection. [12,13]

How Is Syphilis Diagnosed in Pregnancy?

Healthcare providers will typically use two syphilis testing methods to diagnose the condition: VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin). VDRL and RPR tests detect antibodies your body produces when infected with Treponema pallidum. [3]

The VDRL and RPR tests are non-specific screening tests, meaning they can indicate the presence of antibodies associated with syphilis but do not directly detect the bacterium itself. If these syphilis screening tests yield positive results, further confirmatory testing is required. [13]

If you are at high risk for syphilis or it is hard for you to go to regular prenatal care visits, the CDC recommends being tested for syphilis when you have a pregnancy test and treatment, even without the follow-up confirmatory testing, to reduce the chances of missing an opportunity to prevent congenital syphilis. [13]

If you test positive for syphilis during pregnancy, be sure to get treatment right away to avoid infecting your baby. If you are diagnosed with and treated for syphilis during your pregnancy, your doctor should do follow-up testing for at least one year to make sure that your treatment is working. [1]

The child will require follow-up tests one, two, four, six, and 12 months following treatment to ensure the infection is no longer present. Children diagnosed with neurosyphilis—in which the infection has spread to the brain and spinal cord—will also require a follow-up cerebrospinal fluid (CSF) analysis six months after treatment, and if the test comes back positive, the child will need an additional round of penicillin treatment. [10]

Fortunately, with early and complete treatment, the health prognosis of children with congenital syphilis is favorable. [10]

How to Reduce the Spread of Syphilis and Prevent Congenital Syphilis

You can prevent your baby from getting congenital syphilis by testing regularly for syphilis and especially as soon as you find out you are pregnant, as recommended by the Centers for Disease Control (CDC), the US Preventive Services Task Force (USPSTF), the American College of OBGYNs (ACOG) and the American Academy of Pediatrics. [14] Most states mandate screening for syphilis in all pregnant women at the first prenatal visit, and some mandate screening at the time of delivery. [14]

Early and repeated testing is recommended for syphilis in pregnancy, particularly in people living in areas with higher numbers of reported syphilis cases or people with other risk factors for exposure to STIs and syphilis. [3] In most cases of congenital syphilis, pregnant women received prenatal care but were not screened and treated for syphilis early enough during the pregnancy to prevent transmission to the fetus. [14]

Some of the proposed ways to you can avoid syphilis infection in the first place and have a healthy pregnancy is to [15]:

• Seek early prenatal care and return regularly for all your visits – Routine prenatal visits your healthcare providers to perform screenings and tests to identify syphilis infection promptly and monitor for any problems.
• Test regularly for syphilis even if you aren’t pregnant or don’t have symptoms.
• Don’t forget about your partner (s) – Treating both partners helps prevent re-infection and reduces the risk of transmission to your unborn baby. It is critically important that you notify all of your sexual partners if you test positive for syphilis to prevent continued spread of this STI.
• Complete your syphilis treatment as prescribed.
• Learn about the signs and symptoms of syphilis – Known as the great imitator, syphilis can cause a range of subtle symptoms made even more complicated by all of your pregnancy-related changes. Know what to look for. Be honest with your provider so they can do their job. Talking to your healthcare provider honestly and openly about your sexual health and risk factors for STIs both before and during pregnancy makes it easier for them to ensure you have a healthy pregnancy.
• Education and awareness – Providing education and raising awareness about syphilis and its risks during pregnancy is crucial. Healthcare providers should inform pregnant individuals about syphilis, its consequences, and the importance of prenatal care and screening.
• Practice safe sex, always, even when pregnant – Using barrier methods (such as condoms and dental dams) correctly and consistently and cleaning and not sharing sex toys can help reduce the risk of syphilis transmission during your pregnancy.
• Partner notification and contact tracing – Identifying and notifying sexual partners who may have been exposed to syphilis is important to ensure their testing, treatment, and prevention of further transmission.
• Health equity and access to care – Addressing social determinants of public health, reducing barriers to healthcare access, and promoting health equity are crucial for preventing congenital syphilis. Ensuring all individuals have access to timely and affordable prenatal care and appropriate syphilis testing and treatment is essential.

Hone in on Your Health with Everlywell

Given that almost half of pregnancies (45 percent) in the U.S. are unplanned, and that at least one in four people don’t learn that they are pregnant until 7 weeks or later [16], you might want to test more often for STIs like syphilis if you are sexually active and not using birth control reliably. Prevention makes sense because syphilis is so easily and effectively treated and because the effects of syphilis in pregnancy can be so devastating.

The Everlywell at-home Syphilis Test will detect antibodies associated with the Treponema pallidum bacterium. If your test comes back with abnormal results, we’ll put you in contact with a clinician to confidentially discuss your symptoms and treatment plan.

Prioritize your sexual health today with Everlywell’s online STD treatment.

Related Content

Can You Get Syphilis Without Having Sex?

Syphilis Tongue: Here's What to Know

Ocular Syphilis: A Quick Guide

References

1. Congenital Syphilis – CDC Fact Sheet. CDC. Published April 11, 2023. URL. Accessed June 16, 2023. .
2. National Overview of STDs, 2021. CDC. Published May 16, 2023. URL. Accessed June 16, 2023. .
3. Syphilis, Detailed Fact Sheet. CDC. URL. Accessed June 26, 2023. .
4. Fang J, Partridge E, Bautista GM, Sankaran D. Congenital Syphilis Epidemiology, Prevention, and Management in the United States: A 2022 Update. Cureus. 2022;14(12):e33009. Published 2022 Dec 27. doi:10.7759/cureus.33009. URL. Accessed June 12, 2023.
5. Syphilis – CDC Basic Fact Sheet. CDC. Published February 10, 2022. URL.Accessed June 16, 2023. .
6. Tsai S, Sun MY, Kuller JA, Rhee EHJ, Dotters-Katz S. Syphilis in Pregnancy. Obstet Gynecol Surv. 2019;74(9):557-564. doi:10.1097/OGX.0000000000000713. URL. Accessed June 12, 2023.
7. Rac MW, Revell PA, Eppes CS. Syphilis during pregnancy: a preventable threat to maternal-fetal health. Am J Obstet Gynecol. 2017;216(4):352-363. doi:10.1016/j.ajog.2016.11.1052. URL. Accessed June 12, 2023.
8. Pregnancy, STI Effects and Burden, Syphilis. CDC. URL. Accessed June 26, 2023. .
9. Congenital Syphilis. NORD. URL. Accessed June 12, 2023.
10. Arnold SR, Ford-Jones EL. Congenital syphilis: A guide to diagnosis and management. Paediatr Child Health. 2000;5(8):463-469. doi:10.1093/pch/5.8.463. URL. Accessed June 12, 2023.
11. Syphilis, Pregnancy and HIV, Viral Hepatitis, STD, and TB Prevention. CDC. URL. Accessed June 27, 2023. .
12. Alexander JM, Sheffield JS, Sanchez PJ, Mayfield J, Wendel GD Jr. Efficacy of treatment for syphilis in pregnancy. Obstet Gynecol. 1999;93(1):5-8. doi:10.1016/s0029-7844(98)00338-xURL. Accessed June 12, 2023.
13. STI Treatment Guidelines, 2021. CDC. URL. Accessed June 25, 2023. .
14. Screening for Syphilis in Pregnant Women. Am Fam Physician. 2019;99(8): URL. Accessed June 24, 2023. .
15. Reduce congenital syphilis — STI 04. OASH. URL. Accessed June 18, 2023. .
16. Branum AM, Ahrens KA. Trends in Timing of Pregnancy Awareness Among US Women. Matern Child Health J. 2017;21(4):715-726. doi:10.1007/s10995-016-2155-1 URL. Accessed June 12, 2023.