8.7 Embryopathies

Non-viral pathogens

  • Toxoplasmosis:
    The toxoplasmosis pathogen is an intracellular parasite (toxoplasma gondii), which gets through the placenta and infects the embryo. Pregnant women should avoid household pets and should consume no raw meat or non-pasteurized milk.
    In the case of a first infection, the danger of infection at the beginning of the pregnancy is limited but is elevated towards the end.
    The earlier the infection occurs, the worse it is. The parasite lives in the blood, in the tissues, in the epithelial cells and in the leucocytes. The consequences of an infection are extremely grave in the course of the embryonic period: cerebral abnormalities (calcification) and ophthalmic abnormalities (chorioretinitis), microcephalia, microphtalmia and hydrocephalus. If the infection occurs at this point it is often lethal.

  • Congenital syphilis:
    In Europe congenital syphilis is seldom encountered. In America, on the other hand, the disease is becoming an increasingly larger problem (frequency of 0.1% as estimated by the US Preventive Services Task Force organization, 1989).
    The pathogenic agent is Treponema pallidum, which is transmitted via sexual intercourse. An infected mother transfers the disease to her child. The treponema pallidum is always able to get through the placenta barrier. Nevertheless, it seems the fetus is only threatened by an infection after the 4th month. It is the first infection of the mother during pregnancy that causes a congenital syphilis in the baby. This becomes worse the longer the infection lasts. A treatment with antibiotics (penicillin) kills the microorganism. The early symptoms of an untreated congenital syphilis are mental deficiency, hydrocephalus, deafness, blindness, bone malformations and pathognomic abnormalities of the teeth (Hutchinson's teeth).
    To the late symptoms number the Hutchinson triad: keratitis, deafness, "screwdriver teeth".

Medications, hormones and chemical products

  • Thalidomide:
    Thalidomide is an example for the catastrophic, teratogenic effects of a medication that were not detected despite animal trials. This substance was introduced in 1959 and, as a widely used medication against nausea and for tranquilizing, was prescribed for pregnant women. The abnormalities that resulted in children included effects to the limbs (meromelia and amelia), the heart, the kidneys, the intestines and the external ear.

More info

Interesting site (French)

Chronological table
of the abnormalities caused by thalidomide

  • Vitamin A and retinoic acid:
    Special attention must also be given to vitamin A and its derivatives. Retinol is highly teratogenic in animals, but exhibits no effects in humans. Nevertheless, the daily intake of Retinol should not exceed 6,000 UI.
    Retinoic acid, on the other hand, which is often employed in dermatology for healing acne, (Roaccutane ® Isotretinoin) is responsible in 20% of the cases for a polymalformative syndrome that includes cranio-facial abnormalities and those of the CNS and the circulatory system. The critical period, for effects on the embryo, range from the 3rd to the 5th week. Utilization of retinoic acid during pregnancy is forbidden.

  • Diethylstilboestrol:
    Diethylstilboestrol is a teratogenic substance that leads to anomalies of the vagina and the uterus in female embryos. Three kinds of abnormalities are seen: a vaginal adenosis, erosions of the cervix and transversal cleavages in the vagina. A somewhat more seldom but characteristic disorder occurs only many years after exposure in utero, namely at the age of 16-22. Here the development of a vaginal adenocarcinome is involved.

  • Antibiotics:
    During pregnancy, antibiotics must be taken with caution.
    Tetracycline, for example, leads to a coloration of the teeth.
    Streptomycin derivates lead to damage of the 8th cerebral nerve which, in turn, leads to hearing problems.
    Penicillin, on the other hand, can be taken during pregnancy.

  • Drugs:
    Among the various drugs, cocaine plays an important role since it is consumed by an increasing number of pregnant women. In 1990, this drug damaged 300,000 to 400,000 newborns. Cocaine, which passes through the placental barrier, can bring about an addiction in the child. The consumption of cocaine leads to retarded growth, to malformations of the circulatory system and to elevated mortality and morbidity (frequency of disease) of the fetus.

The list of teratogenic medications and substances is still very long. For a detailed list, and especially concerning alcohol and tobacco, we refer you to the fetal period module and to the pop-up window.

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