The teratogenic effect of drugs causes the appearance of defects, as well as anomalies in the development of the child due to their use by the mother during pregnancy. Teratogenesis develops under the influence of factors acting from the outside on the developing organism of the fetus, it is also possible under the influence of hereditary diseases.
What causes it?
Teratogenic effect is due to the passage of drugs or their transformation products through the barrier between the uterus and the placenta, resulting in disruption of the formation of organs and tissues of the embryo.
Critical Periods
At different stages of pregnancy, various damages occur associated with the chronological formation of body structures - these are critical periods. The most dangerous in terms of the development of serious disorders are the first 2-3 months of pregnancy. It should be noted that at earlier periods, under the influence of such factors, violations also occur.in the developing organism, however, they are incompatible with life: a miscarriage occurs (spontaneous abortion). Critical periods for different organs are different: 23-28 days of intrauterine development are important for the brain, 23-45 days for the organ of vision, limbs are formed on 28-56 days and so on.
What factors cause?
The following factors cause teratogenic effects: drugs, infections (rubella, herpes, cytomegalovirus, parvovirus, syphilis, toxoplasmosis), metabolic disorders in pregnant women (endemic goiter, decompensated diabetes mellitus, prolonged hyperthermia, androgen-producing tumors), drugs (androgens, methotrexate, captopril, enalapril, iodides, thiamazole, tetracyclines, thalidomide, valproates, warfarin, busulfan), ionizing radiation (radiation therapy for cancer, radioactive iodine therapy, radioactive fallout) and more.
Impact features
These factors affect with some peculiarities. The teratogenic effect is dose related. In addition, before the impact of any factor in the subthreshold values of defects in the fetus is not formed. The teratogenic effect in different biological species and even in different representatives of the same species can be different, which is associated with the individual characteristics of metabolism (absorption, distribution and excretion in the mother's body and direct penetration through the utero-placental barrier). However, when the mother is exposed to infectionit is not possible to determine the threshold dose.
Spread of factors
Teratogens are widely found in the environment. As a result of research, it was found that a woman takes about 3-4 medicinal substances during pregnancy. In addition, pregnant women may come into contact with various harmful compounds at work or at home. The teratogenic effect of drugs must be established in studies: the relationship between the direct effect of the factor and the appearance of the defect must be proven with confirmation by epidemiological data. In addition, the influence of the factor must coincide with the critical periods.
