Ana was 24 years old and 18 weeks pregnant when the result came back. She had felt almost nothing, her prenatal appointments had shown no warning signs, and the pregnancy seemed calm the way every expectant mother hopes it will be. But the VDRL came back positive, with a titer of 1:32, and everything changed. The diagnosis was active syphilis. Without prior treatment, without a treated partner, with almost five months of pregnancy, she and her baby were in real danger, and time was already running out for both of them.

Stories like Ana's repeat themselves by the thousands every year in Brazil. Congenital syphilis, the kind passed from mother to child inside the womb, remains one of the most frequent and, at the same time, most preventable causes of death and severe complications in newborns in the country. Preventable because a simple test and an accessible antibiotic are all it takes for it to never happen.

How the Bacteria Reaches the Baby

Syphilis is caused by a bacterium called Treponema pallidum, transmitted mainly through unprotected sexual contact. When a pregnant woman is infected, this bacterium can cross the placenta and reach the fetus at any stage of pregnancy, but especially from the second trimester onward, when the placenta becomes more permeable to what circulates in the mother's blood.

Here is the alarming point: the more recent the infection, the more bacteria are actively circulating and the greater the chance that the baby will be contaminated. In cases of untreated primary or secondary syphilis, this risk can exceed 80%. It is not a vague estimate. It is a number that should be discussed more often.

What Happens to the Mother

Part of the problem is that syphilis rarely gives clear signs.

In the primary stage, a painless sore appears in the genital area, known as a hard chancre, which disappears on its own in a few weeks and gives the woman the impression that it has passed.

In the secondary stage, the infection spreads throughout the body and can cause:

  • Red blotches on the skin (including on the palms of the hands and soles of the feet, characteristic of the disease)
  • Low-grade fever
  • Malaise
  • Enlarged lymph nodes

After that comes the latent stage: with no visible symptoms, but with the bacterium still alive and present.

It is precisely in this silent stage that many women arrive at prenatal care without knowing what they are carrying. And it is in this stage that the baby is at the greatest risk, because the infection continues its course inside the womb without anyone noticing.

The Consequences for the Baby

When syphilis is not treated during pregnancy, the consequences for the baby can be extremely serious. The baby may be stillborn, born prematurely, with very low birth weight, or apparently healthy but carrying sequelae that will only appear months or years later. There is no single outcome: the disease has many ways of causing damage.

Early and Late Congenital Syphilis: Two Distinct Scenarios

When signs appear in the first two years of life, it is called early congenital syphilis. The baby may present with:

  • Stuffy nose with persistent discharge
  • Spots or blisters on the skin
  • Swollen belly due to enlarged liver and spleen
  • Jaundice
  • Anemia
  • Bone pain that prevents the baby from freely moving his or her arms and legs

Many times, the baby cries inconsolably when touched, simply because he or she is in pain, and this is often mistaken for colic or temperament.

When diagnosis is delayed even further, the disease enters its late stage, after two years of life, and the condition becomes much harder to reverse. The sequelae include:

  • Permanent deafness
  • Blindness from eye inflammation
  • Sunken nose in the middle of the face in a saddle shape
  • Malformed teeth and bones
  • Neurological impairment that follows the child forever

These are sequelae that a simple penicillin injection during prenatal care would have prevented.

The Diagnosis: Understanding the Tests

The test that screens for syphilis is called VDRL, and it works by measuring the inflammatory reaction that the body produces in response to the infection. The result comes in the form of a titer, which is nothing more than a sequence of blood dilutions: 1:2, 1:4, 1:8, 1:16, 1:32 and so on. The higher the number, the more intense the infection at that moment. A titer of 1:32 indicates much more bacterial activity than a titer of 1:4, for example.

But the VDRL alone does not confirm the diagnosis. To confirm that it is truly syphilis, a second test is needed, called a treponemal test, such as FTA-Abs or CLIA, which identifies specific antibodies against the bacterium. The two together form the complete diagnosis.

Brazilian protocol recommends that this screening be done at three moments:

  1. In the first trimester of pregnancy
  2. In the third trimester
  3. At the time of delivery

Any altered result requires immediate investigation and treatment.

Treatment During Pregnancy: Why Penicillin is Irreplaceable

There is no safe alternative to penicillin for treating syphilis during pregnancy. Other antibiotics may work outside of pregnancy, but they do not cross the placenta effectively enough to protect the baby. For pregnant women with confirmed penicillin allergy, the protocol provides for a desensitization process in a hospital setting before starting treatment. There is no shortcut in this case.

The form, dose, and duration of treatment depend directly on the stage the infection is in, and this is where the VDRL titer comes in as an essential clinical guide.

Benzathine Penicillin

In more recent forms, such as primary, secondary, and recent latent syphilis with less than one year of progression, a single dose of benzathine penicillin of 2.4 million units, given as an intramuscular injection divided between both buttocks, is already sufficient. Benzathine is a slow-release version of the antibiotic: it enters the body gradually over days, which is exactly what is needed when the infection is still in an early stage.

When the infection is older, with more than one year of progression or with unknown duration, treatment needs to be more prolonged:

  • Three weekly doses of benzathine penicillin
  • One dose per week for three consecutive weeks
  • Totaling 7.2 million units

The detail matters: if the interval between doses exceeds seven days, for any reason, the entire cycle must be restarted.

Crystalline Penicillin

Crystalline penicillin comes into play in more serious situations. Unlike benzathine, it is injected directly into the vein and acts much more rapidly, making it indispensable when the bacterium has already compromised the central nervous system, a condition called neurosyphilis. In these cases, benzathine simply cannot penetrate the fluid surrounding the brain and spinal cord in sufficient quantity to eliminate the infection.

Treatment with crystalline penicillin is done in a hospital setting, every four hours, for ten to fourteen consecutive days.

Besides neurosyphilis, crystalline penicillin is also indicated when treatment with benzathine did not produce the expected response, that is, when the VDRL titer does not drop as it should after complete treatment.

The Titer as a Guide to Cure

After treatment, the VDRL does not go to zero overnight, and that does not mean failure. What is expected is a progressive drop in titer over time:

  • At least two dilutions in six months for recent forms
  • In twelve months for late forms

Someone who starts at 1:32 should be at most 1:8 in six months. If the titer stays the same or rises, retreatment is mandatory and immediate.

This is why during pregnancy, VDRL must be repeated every month. It is not excessive testing, it is active monitoring of a disease that does not forgive those who wait.

Criteria for Baby Protection

It is worth emphasizing a point that many people do not know: treatment of the pregnant woman is only considered adequate to protect the baby if three conditions are met at the same time:

  1. The regimen must be correct for the stage of the disease
  2. Treatment must have been completed at least 30 days before delivery
  3. The partner also must have been treated

If any of these criteria fails, the newborn is automatically considered at risk and must be investigated, regardless of the baby's own test results.

What Happens With the Newborn

In the baby, diagnosis is made with VDRL in umbilical cord blood or in a venous blood sample. When the baby's titer is higher than the mother's, this is a strong sign of active infection.

Depending on the clinical picture, the following may still be necessary:

  • Lumbar puncture to analyze the fluid around the brain
  • X-rays of the bones
  • Eye examination
  • Hearing evaluation
  • Liver function tests

Treatment, when indicated, is done with crystalline penicillin for ten to fifteen days, in doses calculated by the baby's weight and gestational age, always within the hospital.

A Disease That Should Not Exist in 2026

Congenital syphilis is, before anything else, a failure of the health system. Not of an uninformed mother, not of a careless family: of the system. Because we are talking about a disease that is resolved with an inexpensive test and an antibiotic that has existed for decades, and yet the numbers remain alarming in Brazil, with tens of thousands of cases every year.

If you are pregnant or planning to become pregnant:

  • Do not delay the VDRL
  • If the result comes back positive, treat without delay
  • If there is a partner in this situation, he needs to be treated at the same time, because a cycle only breaks when both sides of the chain are treated

Important warning: This text is exclusively informative and educational in nature, produced based on scientific evidence and protocols from Brazil's Ministry of Health. It does not replace a medical consultation. Only a qualified healthcare professional can evaluate your case, request appropriate tests, and indicate the correct treatment. If you have questions or suspicions about your health or your baby's health, seek medical care immediately.