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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Obstetrics

Understanding Congenital Toxoplasmosis

At a Glance

Congenital toxoplasmosis occurs when a pregnant person contracts the Toxoplasma gondii parasite for the first time and passes it to their baby. Early detection allows doctors to use medications like spiramycin to protect the baby and monitor fetal development with specialized ultrasounds.

Finding out about a potential infection during pregnancy can be overwhelming. It is natural to feel a rush of worry, but it is important to know that you are not alone, and there is a clear medical path forward. Congenital toxoplasmosis is a condition that occurs when the Toxoplasma gondii parasite is passed from a pregnant person to their developing baby [1]. While the word “congenital” simply means “present at birth,” it does not mean your baby’s health is already determined [2]. Early detection allows your medical team to take proactive steps to protect your baby’s health [3].

Understanding the Parasite

Toxoplasma gondii is a very common parasite found worldwide [4]. People usually come into contact with it in a few ways:

  • Ingesting microscopic eggs from soil or water contaminated by cat feces [5][6].
  • Eating undercooked or raw meat that contains the parasite [7].
  • Handling unwashed fruits or vegetables that grew in contaminated soil [8].

Why This Happened Now

It is common for parents to feel guilt, wondering if they should have stayed away from cats or been more careful with food. However, it is important to remember that most people who get this infection never even know it, as it often feels like a mild flu or has no symptoms at all [9].

A Note About Cats: If you have an indoor-only cat fed a commercial diet, they pose virtually no risk of transmitting toxoplasmosis [5]. You do not need to rehome your pet. As a precaution, simply have someone else scoop the litter box daily, or wear gloves and a mask if you must do it yourself, and wash your hands thoroughly afterward [8].

Crucially, the parasite only poses a risk to the baby if you experience your primary infection—meaning your very first time ever catching it—while you are pregnant [1]. If you had the infection years ago, your immune system likely already knows how to control it, which protects your baby [10][11].

Stabilizing Facts for Parents

While the diagnosis is serious, there are several key pieces of information that can help lower the “panic” level:

  1. Risk Changes Over Time: The chance of passing the infection to the baby is actually lowest in the first trimester (the first 12 weeks) and highest in the third trimester [1].
  2. Severity Often Decreases Later in Pregnancy: Even though transmission is more likely later in pregnancy, infections acquired later are much more likely to be mild or even asymptomatic (showing no symptoms) at birth [12][2].
  3. Treatment is Available: Doctors can use medications like spiramycin to help prevent the infection from crossing the placenta [13]. If the baby is already infected, other medications like pyrimethamine-sulfadiazine can be used to treat the infection directly and reduce the risk of long-term health issues [14][15].
  4. Proactive Monitoring: Modern prenatal care uses advanced tools like PCR testing of amniotic fluid and specialized ultrasounds to monitor the baby’s development and ensure the treatment is working [16][17].

Moving Forward

Your medical team will likely use a combination of blood tests, such as IgG avidity (which helps determine exactly when the infection happened), to tailor a plan for you [18]. Early treatment is the most effective way to improve the outlook for your baby, and being diagnosed now means you have the opportunity to act quickly [3][19]. Managing a high-risk pregnancy is stressful, and it is normal to feel anxious; focusing on the steps you can take today is a powerful way to care for your baby [20][21].

Common questions in this guide

Do I need to get rid of my cat if I am pregnant to avoid toxoplasmosis?
No, you do not need to rehome your pet. Indoor-only cats fed a commercial diet pose virtually no risk of transmitting toxoplasmosis. To be safe, simply have someone else scoop the litter box daily, or wear gloves and a mask if you must do it yourself.
When during pregnancy is the risk of passing toxoplasmosis to my baby the highest?
The chance of passing the infection to your baby is highest during the third trimester. However, infections acquired later in pregnancy are usually milder and often have no symptoms at birth. The risk of transmission is actually lowest during the first trimester.
What treatments are available for congenital toxoplasmosis during pregnancy?
Doctors can prescribe medications like spiramycin to help prevent the infection from crossing the placenta to your baby. If testing confirms the baby is already infected, a combination of pyrimethamine and sulfadiazine can be used to treat the infection directly and reduce the risk of long-term health issues.
If I had toxoplasmosis years ago, is my baby currently at risk?
If you experienced your first toxoplasmosis infection years before becoming pregnant, your immune system likely already knows how to control it. This prior immunity generally protects your developing baby from the infection.
How will my doctor monitor my baby for a toxoplasmosis infection?
Your medical team can use specialized ultrasounds to track your baby's development. They may also test your amniotic fluid using a highly sensitive PCR test to check if the infection has crossed the placenta and reached the baby.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my lab work, when is it estimated that I first contracted the infection?
  2. 2.What is the current risk level of transmission to the baby based on how far along I am?
  3. 3.Has the infection crossed the placenta, and how do we determine that (e.g., amniocentesis or ultrasound)?
  4. 4.Which medication is most appropriate for my situation—spiramycin to prevent transmission or pyrimethamine-sulfadiazine for a confirmed fetal infection?
  5. 5.How often will we need to perform follow-up ultrasounds to monitor the baby's development?
  6. 6.What specialized care (like a pediatric ophthalmologist or neurologist) should we plan for after the baby is born?

Questions For You

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References

References (21)
  1. 1

    Ocular Findings in Infants with Congenital Toxoplasmosis after a Toxoplasmosis Outbreak.

    Conceição AR, Belucik DN, Missio L, et al.

    Ophthalmology 2021; (128(9)):1346-1355 doi:10.1016/j.ophtha.2021.03.009.

    PMID: 33711379
  2. 2

    Is Toxoplasma gondii type related to clinical outcome in human congenital infection? Systematic and critical review.

    Rico-Torres CP, Vargas-Villavicencio JA, Correa D

    European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology 2016; (35(7)):1079-88 doi:10.1007/s10096-016-2656-2.

    PMID: 27146878
  3. 3

    One severe case of congenital toxoplasmosis in China with good response to azithromycin.

    Li J, Zhao J, Yang X, et al.

    BMC infectious diseases 2021; (21(1)):920 doi:10.1186/s12879-021-06619-1.

    PMID: 34488656
  4. 4

    A Comprehensive Subcellular Atlas of the Toxoplasma Proteome via hyperLOPIT Provides Spatial Context for Protein Functions.

    Barylyuk K, Koreny L, Ke H, et al.

    Cell host & microbe 2020; (28(5)):752-766.e9 doi:10.1016/j.chom.2020.09.011.

    PMID: 33053376
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    Toxoplasma gondii genotypes and frequency in domestic cats from Romania.

    Györke A, Balea A, Borșan S, et al.

    BMC veterinary research 2024; (20(1)):369 doi:10.1186/s12917-024-04210-9.

    PMID: 39152437
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    Prevalence of Toxoplasma gondii in Galapagos birds: Inference of risk factors associated with diet.

    Mosquera JD, Valle CA, Nieto-Claudin A, et al.

    PloS one 2023; (18(7)):e0287403 doi:10.1371/journal.pone.0287403.

    PMID: 37405972
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    All about Toxoplasma gondii infections in pigs: 2009-2020.

    Dubey JP, Cerqueira-Cézar CK, Murata FHA, et al.

    Veterinary parasitology 2020; (288()):109185 doi:10.1016/j.vetpar.2020.109185.

    PMID: 33271424
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    First report of Toxoplasma gondii sporulated oocysts and Giardia duodenalis in commercial green-lipped mussels (Perna canaliculus) in New Zealand.

    Coupe A, Howe L, Burrows E, et al.

    Parasitology research 2018; (117(5)):1453-1463 doi:10.1007/s00436-018-5832-8.

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    Function and mechanism of dopamine receptor D2 (DRD2) in neuroinflammation and behavioral disorders in C57BL/6J mice infected with Toxoplasma gondii TgCtWh6 strain.

    Sun H, Xie X, Li Y, et al.

    Brain, behavior, and immunity 2026; (131()):106136 doi:10.1016/j.bbi.2025.106136.

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    Innate, adaptive, and cell-autonomous immunity against Toxoplasma gondii infection.

    Sasai M, Yamamoto M

    Experimental & molecular medicine 2019; (51(12)):1-10 doi:10.1038/s12276-019-0353-9.

    PMID: 31827072
  11. 11

    Toxoplasma gondii tkl1 Deletion Mutant Is a Promising Vaccine against Acute, Chronic, and Congenital Toxoplasmosis in Mice.

    Wang JL, Liang QL, Li TT, et al.

    Journal of immunology (Baltimore, Md. : 1950) 2020; (204(6)):1562-1570 doi:10.4049/jimmunol.1900410.

    PMID: 31996457
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    Congenital toxoplasmosis.

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    Seminars in pediatric neurology 2025; (54()):101203 doi:10.1016/j.spen.2025.101203.

    PMID: 40701684
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    Congenital Toxoplasmosis: The State of the Art.

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    Frontiers in pediatrics 2022; (10()):894573 doi:10.3389/fped.2022.894573.

    PMID: 35874584
  14. 14

    The prevention of congenital toxoplasmosis using a combination of Spiramycin and Cotrimoxazole: The long-time experience of a tertiary referral centre.

    De Santis M, Tartaglia S, Apicella M, et al.

    Tropical medicine & international health : TM & IH 2024; (29(8)):697-705 doi:10.1111/tmi.14021.

    PMID: 38842439
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    Comparison of adverse reactions of spiramycin versus pyrimethamine/sulfadiazine treatment of toxoplasmosis in pregnancy: is spiramycin really the drug of choice for unproven infection of the fetus?

    Prasil P, Sleha R, Kacerovsky M, Bostik P

    The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 2023; (36(1)):2215377 doi:10.1080/14767058.2023.2215377.

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    Employing digital PCR for enhanced detection of perinatal Toxoplasma gondii infection: A cross-sectional surveillance and maternal-infant outcomes study in El Salvador.

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    IgG Avidity Test in Congenital Toxoplasmosis Diagnoses in Newborns.

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  20. 20

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This page provides educational information about congenital toxoplasmosis during pregnancy. Always consult your obstetrician or maternal-fetal medicine specialist for a formal diagnosis and treatment plan tailored to your specific pregnancy.

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