What are the risks of toxoplasmosis during pregnancy?

If you get toxoplasmosis for the first time when you’re pregnant, or up to three months before you conceive, there’s a risk that the infection can:

  • pass to and damage your unborn baby (mother-to-child transmission)
  • cause miscarriage or stillbirth

The risk of problems varies, depending on when you become infected during your pregnancy.

Risk of miscarriage and health problems

If you get toxoplasmosis in the early stages of pregnancy, the risk of miscarriage is increased.

It’s rare for the infection to pass to the baby during early pregnancy, but if it does, it can cause serious health problems.

In later pregnancy, the infection more commonly passes to the baby. For example:

  • the risk of toxoplasmosis affecting the unborn baby is lower in early pregnancy, at 6% to 26% from 7 to 15 weeks.
  • in later pregnancy, this risk rises to 32% to 93% from 29 to 34 weeks.

However, babies infected during later pregnancy are less likely to develop serious health problems.

How common is toxoplasmosis during pregnancy?

The risk of getting toxoplasmosis when you’re pregnant is very low. From 1981 to 1992, a total of 423 cases of toxoplasmosis related to pregnancy were reported in England and Wales. During this time, on average about 667,000 babies were born each year.

One study suggests that, in the UK, about three in every 100,000 babies are born with congenital toxoplasmosis. Congenital means present from birth.

Causes of toxoplasmosis

Toxoplasmosis infection is caused by a parasite called toxoplasma gondii. This parasite can be found in:

  • undercooked or raw meat
  • raw cured meat, such as salami or parma ham
  • unpasteurised goats’ milk
  • cat faeces
  • soil or cat litter contaminated with infected cat faeces

Sheep can also carry the toxoplasma parasite.

A European study found that, in pregnant women, toxoplasmosis was usually caused by eating undercooked meat and cured meat. Less commonly, it was caused by contact with contaminated soil.

Symptoms of toxoplasmosis

Healthy women can have toxoplasmosis without knowing, because it usually has no symptoms. However, in some cases, there may be symptoms such as:

  • mild flu-like symptoms, for example, aching muscles and a high temperature
  • swollen lymph nodes (glands that are part of your immune system), particularly in your throat or armpits

The incubation period (time between becoming infected and showing symptoms) for toxoplasmosis is 5-23 days. It can take four to eight weeks for the infection to pass to the baby.

Most babies born with congenital toxoplasmosis have no symptoms. However, symptoms can develop later in life, sometimes months or years later, usually affecting the eyes.

Avoiding toxoplasmosis infection

In the UK, pregnant women are not routinely screened for toxoplasmosis. It’s therefore important that you know how to avoid toxoplasmosis infection.

For more information, see Why shouldn’t I change the cat litter if I’m pregnant?

Read the answers to more questions about infections during pregnancy.


NHS Choices

Published Date 2010-07-23

Last Review Date 2010-05-16

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