Infectious Agents

Common Infectious Agent

There are many infections that can harm a developing fetus. The infections are able to cross the placenta and thefetus does not have a fully developed immune system that is able to cope with the infections. Here are a few of the more common infections known to have teratogenic effects: 

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Rubella in Pregnancy

Most people have ben vaccinated against the Rubella ( or German Measles) Virus at school, perhaps as part of the MMR Vaccine. This vaccination however does not last as long as was previously thought and so pregnant women are now advised to check they are immune to Rubella very early on or before trying to concieve.

Rubella is most dangerous in the first trimester and has a 90% absolute risk of casing fetal abnormalities including still birth, miscarriage, heart defects and brain defects. Between week 10 and 27 the main risks are to the babies sight and hearing and after week 27 the risk is much lower.

 Parvovirus in Pregnancy

The parvovirus lives in red blood cells and causes firth disease which is common is young children and often termed “slap cheek” . If a pregnant mother contacts the virus early in pregnancy, before week 20, there is a 15% chance of miscarriage. It is also possible for the viris to cause hydrops fetalis. This results from fetal aenemia due to a lack of iron. It can be a fetal form of heart failure or lead to spontaneous abortion.

Toxoplasmosis

Toxoplasmosis is caused by a parasite that is found in raw meat and in cat faeces and if contracted during pregnancy can lead to a condition congenital toxoplasmosis. Congenital toxoplasmosis often leads to miscarriage or if the infant survives it can lead to growth problems, hydroencephaly, epliepsy, blindness or deafness. There is a greater risk to the baby in the final trimester when there is a 70% chance of the baby contracting the infection.

Sexually Transmitted Diseases

STDs can act as teratogens as well as infecting the baby on delivery. Some, like syphilis can cross the placenta and distrupt development. STDs may cause stillbirth, low birth weight,  neurological problems such as brain damage and motor function disorder, blindness, deafness, and other congenital abnormalities and therefore act as teratogens.