Teratogenic substances, consumed by the mother during pregnancy, can damage the embryo in its development. Medicines and environmental toxins comprise the largest class of teratogenic substances. After the thalidomide catastrophe deformities induced by medications have become much rarer. Caution must, though, be exercised before taking any unsupervised medicine during the pregnancy because only very little is known about the interactions of various medications in the embryo. The trend to alternative medicines such as the use of a harmless-appearing phyto-therapeutica can have disastrous consequences to the fetus. Ginko biloba, for example, contains a large concentration of cholchicine that is known to be poisonous for dividing cells. The consumption of alcohol must also be mentioned - it is known with certainty to be a teratogenic substance.
Possible mechanisms for the fetal alcohol syndrome are:
The alcohol induced production of superoxide-radicals that oxidize the cell membranes and thereby can cause cytolysis.
The neural ridge cells are disturbed in their emigration.
Alcohol directly hinders cellular adhesion.
Nicotine abuse during the pregnancy mainly leads to deformities if a genetic predisposition is present. Under certain circumstances nicotine is also a neuro-teratogenic substance. Furthermore, nicotine probably has an influence on placental vessels, which in turn can have negative effects on fetal nourishment.
In addition to the chemical substances just mentioned, new chemical combinations (200 - 500 substances) to be used as pesticides, cosmetics, etc. are being produced constantly and reliable information about toxicity is not available for many of them.
We must not only speak about the possible toxicity of new substances, but also about the excessive consumption of substances, such as vitamin A that, in themselves, are necessary for life. Of vitamin A one knows that when taken excessively during pregnancy it can lead to damage of the embryo/fetus. Thanks to its excellent effects on severe acne, it is employed in the treatment of this condition (e.g., in the form of Accutane ®) and can thereby cause severe damage to the baby, if an unplanned pregnancy occurs.