Toxoplasmosis during pregnancy

By BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 09/29/2014

Toxoplasmosis is a disease due to a parasite called Toxoplasma gondii.

When cats develop this disease, for eating stools or meat of other contaminated animals, the parasite reproduces itself within the their intestine and ends into their excrements. A few days after, this parasite turns infective and moreover resistant to the great majority of disinfectants.

Under certain conditions of temperature and humidity, the parasite is able to live on the ground: it is important to know that infected cats normally look healthy.

Toxoplasma parasite


Even if Toxoplasmosis is one of human being's most common infections worldwide, in the majority of cases it goes unnoticed: its symptoms, when they are visible, are similar to the flu and are present once in a lifetime.

Nevertheless, the parasite normally remains within the body for an indefinite time: it involves no discomfort and stays inactive, despite the immune system does not work well. For this reason, toxoplasmosis is one of the opportunistic infections most alarming in people sick from AIDS.


When a woman has developed immunity to the infection between 6 and 9 moths before she became pregnant, a real risk of transmitting the infection to the baby is very rare. On the other hand, when a pregnant woman gets the disease for the first time, there's 40% of possibilities she transmits the infection to the fetus.

It should be clear that the risk and the seriousness of the baby's infection will also depend on the pregnancy moment the mother is living at that time. For this reason, during the pregnancy many blood tests are made to verify if the future mother had the disease in the past (and became immune), or, on the contrary, if there's the risk she transmits it to the baby,

The probability of a baby's infection while he is forming within the uterus is lower during the first quarter (15%); nevertheless, there's 30% of possibilities during the second quarter, and 65% during the third quarter of pregnancy (in this case, we call it fetal toxoplasmosis).

On the contrary, if the infection is produced in an earlier stage of the pregnancy, the consequences will be more serious than in later stages.

Baby with toxoplasmosis


Normally, 90% of the infected babies (congenital toxoplasmosis) seem normal when they born, although months or years later, between 80 and 90% of them develop serious eye infections.

Later in time, some children can also have:

  • Hearing loss.
  • Mental retardation.
  • Hydrocephalus.
  • Learning problems.
  • Strokes.

Developing the illness while pregnant can also cause fetal death or miscarriage.

How is it spread?

Which are the causes for a pregnant woman to be infected with toxoplasmosis? You can get the disease from:

  • Contact with cats excrements.
  • Eating raw or undercooked meat, infected with the parasite.
  • Eating infected or not washed vegetables, in which an animal can possibly have defecated and that weren't properly washed and disinfected.
  • Blood transfusion from an infected individual to a healthy one.
  • Vertical transmission: the pregnant mother passes the parasite to the fetus via the placenta.

Developing toxoplasma


General recommendations to avoid the contamination of toxoplasmosis, for all those women who are pregnant or have the intention to become mothers, are:

  • Washing their hands with soap before and after touching any food, most of all raw meat. Moreover, not touching their eyes, nose or mouth with dirty hands.
  • Cooking meat thoroughly, because the toxoplasma parasite dies at 72ºC.
  • Not drinking milk or raw eggs.
  • Not eating raw cold meat.
  • Washing and sanitizing fruit and vegetables with products for food hygiene.
  • Avoiding gardening for the contact with soil, where there's the possibility an infected cat defecated.
  • Avoiding the contact with cats: if you have one, pass the activity of looking after it and its feeding onto another person during the pregnancy period.

Following this advice is important: in this way, you could reduce by up to 60% the risk of contagion.

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 Zaira Salvador
Zaira Salvador
BSc, MSc
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI) More information about Zaira Salvador
License: 3185-CV
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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