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Every pregnant woman should be aware that any medicine she takes will have an effect on the fetus, since many chemicals can penetrate the placenta to developing child. Their embryotoxic and fetotoxic effects often lead to embryonic death, delayed skeletal development, reduced body weight gain or an increase in perinatal pathologies.
Relevance of the problem
According to the study, approximately 1% of the development of fetal abnormalities is associated with uncontrolled use of medications by the mother. Therefore, doctors and scientists around the world make it a priority to study medications and their effect on the child’s body in the womb and on the pregnant woman’s body itself. Different stages of pregnancy must be taken into account.
Many scientific centers conduct research into the embryotoxic and teratogenic effects of drugs on the embryo and fetus. They also have a fetotoxic effect on its development.
Thus, the embryotoxic effect in pharmacology is the ability of a drug, when it enters the mother’s body, to have a detrimental effect on the fetus, which leads to its death or developmental abnormalities.
What is embolic action
Embryotoxicity is the damage to a non-implanted blastocyst, which often leads to its death. This effect is caused by medications such as barbiturates, salicylates, athymetabolites, sulfonamides, nicotine and other similar substances.
Embryotoxicity means the effect of medicinal substances coming from the mother’s body on the embryo and fetus, which lead to its death or developmental abnormalities.
Teratogenic effect is the effect on the fetus of medications or biological substances, which causes disturbances in the development of the fetus, and subsequently the child suffers from congenital deformities.
How do medications affect the baby's body in the womb?
Depending on the mechanism of action of medications on the fetus, three directions can be distinguished:
- The first is those that penetrate the placenta and are not able to have a direct effect on the developing fetus.
- The second is through transplacental transition, which means they have a direct effect on the fetus.
- Third, those that, penetrating the placenta, tend to accumulate in the body of the unborn child.
It is worth noting that the toxicity of the drug does not affect the ways it penetrates the fetus.
A teratogenic embryotoxic effect on the fetus can be caused not only by drugs that a woman takes during pregnancy, but also by drugs that were used before conception. As an example, we can take retinoids, which are teratogens with a long latent period. Accumulating in a woman’s body, they can further affect the development of the fetus.
And even taking medications by the child’s father can have an impact on the baby’s congenital pathologies. Most often these are the following medications:
- substances intended for anesthesia;
- antiepileptic drugs;
- "Diazepam";
- "Spironolactone";
- "Cimetidine".
Classification of drugs by risk category during pregnancy
The American Food and Drug Administration - FDA has developed a special classification of drugs that are the most and least dangerous for the fetus during pregnancy:
- A - these include medications that are not able to affect the body of the mother and child. Conducted studies have eliminated this risk. B - drugs that can be taken in limited quantities, and no anomalies in fetal development were subsequently observed. Experiments on animals have ruled out any effect of these medications on the growing organism inside the mother.
- C - these medications, when conducting experiments on animals, had a teratogenic or embryotoxic effect on the embryo. They harm the child’s body, but have reversible consequences. Often, the development of abnormalities in the fetus was not observed.
- D - drugs from this group lead to irreversible consequences and congenital anomalies in a child. When prescribing such drugs, the doctor must weigh their benefits and subsequent risks for the child.
- X - this category of medications can cause persistent fetal developmental anomalies and congenital deformities, since they have a proven teratogenic or embryotoxic effect on both animals and humans. Their use during pregnancy is strictly contraindicated.
What are the consequences of using different groups of drugs during pregnancy?
Here is the embryotoxic effect that various medications can cause in the fetus:
These are just examples of embryotoxic effects; in fact, the list can be continued for a long time, since there are a lot of drugs.
Medicines with teratogenic effects
These include:
The effect of alcohol on fetal development
In addition to the fact that there is a concept of the teratogenic and embryotoxic effects of medicinal substances on the embryo and fetus, it can be noted negative influence alcohol, tobacco and drugs.
A woman who drinks alcohol during pregnancy, even in small doses, risks not only her health, but also the health of her child.
The most common complications include:
Subsequently, the child may experience the following negative manifestations:
- 1/3 of children have fetal alcohol syndrome;
- in 1/3 of cases toxic prenatal changes are observed;
- and only a third of children born will develop without any visible complications.
Fetal alcohol syndrome
It is characterized by three main qualities:
- delay in physical development;
- mental retardation;
- a specific appearance, characterized by a narrow forehead, narrow palpebral fissure, short nose, microcephaly.
These consequences can be prevented if you do not drink alcohol during pregnancy.
The consequences of alcohol syndrome in a child may become dull as he grows, but will not completely disappear. Such a child can be hyperactive, his attention is impaired, which affects his social adaptation.
Also, characteristic features of such a child may be aggressiveness, stubbornness, and poor night sleep.
Embryotic effect of tobacco (nicotine)
Tobacco negatively affects the development of the fetus, and not only when the woman smokes herself. If she is a passive smoker, that is, she is in a room next to people who smoke and inhales the smell of nicotine, she is already harming her unborn child.
Complications of this behavior include:
Smoking can affect the fetus in the following ways:
Conclusion
The embryotoxic effect of many medicinal and non-medicinal substances can lead to severe irreversible consequences. You need to know before taking medications that they will negatively affect the embryo or fetus. Therefore, doctors recommend that young women take a responsible approach to the birth of a child and prepare for birth process, read relevant literature, undergo regular examinations, conduct healthy image life.
Only under such conditions is there a chance to give birth healthy baby, without any deviations. Every time you try to take any drug, remember the embryotoxic effect of the drugs, this can affect your unborn baby. Therefore, discuss every step you take with your doctor.
Hello, Natasha! I think that you can learn about the effect of the drugs you listed on the conception and birth of a child from the annotation to them. Although, of course, even after reading this information, it is impossible to say exactly what the possible effect of these drugs on these things is. Because medications are not always studied for absolutely all factors, especially if the drugs are not taken during pregnancy and breastfeeding, and even more so if they are taken not by women, but by men.
This is exactly the conclusion I come to after reading the annotations. For example, the annotation for Keltikan describes only special instructions regarding pregnancy and lactation.
“The use of the drug during pregnancy and lactation is not contraindicated, but the appropriateness of taking the drug and the dose of the drug are determined by the doctor, depending on the advantage of the benefits of use over the potential risk to the fetus/child.”
From the annotation to Neuromedin:
“Pregnancy and lactation.
The use of the drug is contraindicated during pregnancy and lactation (breastfeeding).
Preparation does not provide teratogenic, embryotoxic action."
What do teratogenic and embryotoxic effects mean? Let's take a look at Wikipedia.
“Teratogenic effect (from the Greek τερατος “monster, freak, ugliness”) - a violation of embryonic development under the influence of teratogenic factors - some physical, chemical (including drugs) and biological agents (for example, viruses) with the occurrence of morphological abnormalities and defects development".
“The embryotoxic effect occurs in the first 3 weeks. after fertilization and consists in negative impact drugs for the zygote and blastocysts located in the lumen of the fallopian tubes or in the uterine cavity (before implantation) and feeding on uterine secretions.”
From these points of view, neuromedin is apparently safe.
I think you are better off with these and other questions regarding conception and birth healthy child, consult a fertility specialist. Experts know better about possible side effects medicines. In addition, I think that first of all, you should pay attention not even to the medications that your husband is taking. And for the diseases for which he is trying to be treated with these medications. Since these medications are intended to treat neurological diseases, and it is your husband’s congenital diseases that may become possible reasons birth of an unhealthy child. But these are just my guesses; it is better to receive more serious advice in person from specialists. Moreover, he can take the listed drugs only for a given period of time. And in other months he takes a number of other medications. I think it would also be a good idea to get some advice about them.
(based on the book by Dr. O.A. Mazur “Capillary therapy cures 95% of diseases”)
According to modern domestic and foreign medical statistics, a significant number of women have extragenital pathology at the time of pregnancy or suffer at various stages of pregnancy, that is, diseases of the extragenital area not directly related to the reproductive organs. According to the same data, up to 80% of women take at least one pharmacological drug during this period. On average, according to foreign experts, each pregnant woman takes 4 medications, not counting vitamins and iron supplements.
It is well known that many drugs cross the fetoplacental barrier and create real concentrations in the blood plasma of the developing fetus, which can adversely affect its development. Weakness in the function of the eliminating (removing toxins) organs of the unborn child can cause a fetotoxic (poisoning the fetus) effect when using even a medicine that is relatively harmless for an adult body. Incorrectly prescribed treatment can ruin a person’s entire future life.after his birth.
Doctors prescribing pharmacological drugs to pregnant women should know and consider the following: the most important points:
- main periods intrauterine development body;
- embryotoxic (poisoning the embryo), teratogenic (causing deformities) and fetotoxic effects of drugs;
- metabolism (transformation in the body) of medications in pregnant women;
- passage of drugs across the placenta and amniotic fluid;
- metabolic characteristics of the developing fetus;
- the main periods of intrauterine development and the effects of drugs on the unborn child.
As is known, the human body in the initial period of its development goes through three stages:
- Period of blasto- and embryogenesis;
- Fruit development period;
- Newborn period.
Therefore, medications used by a pregnant woman can cause three types of effects on the body of the unborn child: embryotoxic, teratogenic and fetotoxic.
Embryotoxic effect
The embryotoxic effect occurs in the first three weeks after fertilization of the egg and consists in the negative effect of drugs on the zygote and blastocysts located in the lumen of the fallopian tubes or in the uterine cavity (before implantation of the fertilized egg into it) and feeding on uterine secretions. Damage and, as a rule, death of the blastocyst is caused by the following pharmacological substances: hormones (estrogens, progestogens, growth hormone, deoxycorticosterone acetate), antimetabolites (mercaptopurine, fluorouracil, cytarabine, etc.), inhibitors of carbohydrate (iodoacetate) and protein (actinomycin) metabolism, salicylates, barbiturates, sulfonamides, fluorine-containing substances, antimitotic agents (colchicine, etc.), nicotine. If the human embryo continues to develop in the mother's womb, it means that it is not damaged.
Teratogenic effect
A teratogenic effect can develop from the third to the tenth week of pregnancy (but many experts rightly suggest extending the boundaries of the dangerous period until the 12th week of pregnancy) and leads to various disturbances in the normal development of the fetus, the occurrence of abnormalities of its internal organs and systems. The type of defect depends on the duration of pregnancy, on which organs are laid down and intensively formed in the embryo during the period of taking the drug. It is believed that the most dangerous period for the development of major defects, that is, for the manifestation of teratogenicity of the drug, is the 3-10th week of intrauterine development, which corresponds to approximately 5-12 weeks after the first day of the last menstruation. Consequently, teratogenic effects are most likely soon after implantation of the egg into the uterine wall, that is, when the woman often does not yet know that she is pregnant.
The likelihood of developing a defect in the fetus depends not only on the pharmacological drug prescribed to the pregnant woman, but also on her age (the likelihood increases if the pregnant woman is under 17 or over 35 years old), on her state of health, the functioning of the drug elimination (removal) organs, the dose of the drug, the duration of its appointment, genetic predisposition to the development of a particular defect.
Based on the degree of risk of developing a teratogenic effect, researchers divide drugs into three groups.
Group 1 of substances that are extremely dangerous for the developing fetus and therefore absolutely contraindicated in pregnant women include: thalidomide, antifolate drugs (methotrexate, trimethoprim, co-trimoxazole), androgens, diethylstilbestrol and hormonal oral contraceptives. It is recommended to stop taking the latter at least 6 months before the planned pregnancy.
Group 2 includes medications that are somewhat less dangerous to the fetus and are prescribed to those suffering from epilepsy, diabetes, malignant neoplasms, and some others. Chronic diseases themselves are, of course, a factor predisposing to the occurrence of a teratogenic effect. However, the potential danger of the teratogenic effect of pharmacological drugs of this group, which includes: antiepileptic drugs (difenin, hexamidine, phenobarbital, valproic acid), alkylating antitumor drugs (embiquine, dopan, sarcolysine, chlorbutin), oral (orally administered) antidiabetic drugs, as well as ethanol (ethyl alcohol) and progesterone.
The 3rd group includes drugs that cause malformations under conditions predisposing to this: the first trimester of pregnancy, young or “old” age of the pregnant woman, high doses of the drug, etc. This group of drugs consists of: salicylates, antibiotics of the chloramphenicol and tetracycline, anti-tuberculosis drugs, quinine, imizin, fluorotane (dangerous for pregnant women - workers in anesthesiology departments), vitamin K antagonists, meprotan, neuroleptics, diuretics, anaprilin.
Fetotoxic effect
On later During pregnancy, the fetal organs are mostly formed, so pharmacological agents can no longer cause large anatomical defects in the fetus. Damage may include prematurity, tissue damage, inhibited or impaired organ function, or impaired behavioral responses. The administration of hormones, androgens or progestogens to a pregnant woman is accompanied by masculinization of the fetus. Iodide, lithium and antithyroid drugs used in large doses provoke the development of goiter. Tetracyclines interfere with the development of teeth and bones; quinolones interfere with cartilage development. Prostaglandin synthetase inhibitors (acetylsalicylic acid and indomethacin) can slow down the onset of labor and cause dysfunction of the cardiovascular system in the fetus, since prostaglandins are involved in maintaining the patency of the ductus arteriosus in the fetus, relaxing its muscles.
Fetotoxic effects occur due to an excessively pronounced and characteristic pharmacological effect on the fetus for a given drug (usually in the last weeks of pregnancy) or an undesirable effect specific to the drug. For example, administration of indomethacin to a pregnant woman results in closure of the ductus arteriosus in her fetus before labor occurs; beta-adrenergic agonists disrupt carbohydrate metabolism in the fetus; aminoglycoside antibiotics have an ototoxic effect on the fetus, that is, they affect the tissues and functions of the inner ear. Clinical experience shows that the administration of certain medications to pregnant women can lead to the development of perinatal (childbirth-related) pathology and even the death of the fetus or newborn child.
Medicines before childbirth
Medicines used on the eve of childbirth can cause negative pharmacological effects in the postnatal (postpartum) period. For example, difficulty breathing through the nose, drowsiness, and difficulty feeding a child occur when using reserpine. The antibiotic chloramphenicol causes vascular collapse and hematopoietic disorders in newborns, since it does not conjugate in them. Vasodilators provoke a decrease in blood supply to the uterus and fetus. When beta blockers are used, the fetus may not respond to hypoxia. Sulfonamide drugs displace bilirubin from its connection with plasma proteins, as a result of which the child is born with jaundice. Anticoagulants and antiplatelet agents increase the risk of bleeding. In children, born of a woman with addiction to opioid drugs, withdrawal syndrome with physical manifestations may develop.
In children whose mothers took psychotropic drugs during pregnancy, mental changes are possible due to a slowdown in the development of the central nervous system. nervous system. In particular, such children may have difficulty learning in the future.
The lack of in-depth studies covering a large number of drugs does not allow clear recommendations for increasing or decreasing doses, so most pregnant women are administered drugs at normal therapeutic doses.
Medicines can enter the fetus’s body through the placenta (transplacental route) and amniotic fluid (amniotic fluid), which it actively absorbs through its tracheobronchial tree and lungs, as well as through the gastrointestinal tract. For most pharmacological drugs, their accumulation in the amniotic fluid is low, but some create significant concentrations, for example the antibiotics ampicillin and oxacillin. This property is used in the treatment of intrauterine infections of the fetus.
Features of metabolism in the fetus
Important role In the processes of metabolism (biochemical transformation) of drugs, the function of the liver plays a role, which in the fetus is immature both functionally and morphologically. The functional maturation of the liver in the fetus and the appearance of drug-metabolizing enzymes in it occurs in parallel with histological (tissue) maturation until the moment of birth. However, full metabolism is possible only during postnatal development. Insufficient inactivation of drugs by the fetal liver leads to the fact that a number of drugs (barbiturates, narcotic analgesics, indirect anticoagulants and many others) have a more pronounced toxic effect on the fetus than on the maternal body.
From the environment, toxic elements and their compounds migrate to various ecosystems and along food chains, reaching high concentrations in plants and animals of different nutritional levels, and enter the human body with food.
Penetration of harmful substances into the human body can occur directly from water and air.
So-called teratogenic factors play a major role in the occurrence of congenital malignancies. Teratology- a science that studies the causes, development and prevention of congenital malformations. The term “congenital defects” should be understood as persistent morphological changes in an organ or the entire organism that go beyond variations in their structure. Congenital malformations occur in utero as a result of disruption of the developmental processes of the embryo or (much less often) after the birth of a child, as a consequence of disruption of the further formation of organs.
Environmental factors that have a damaging effect on the embryo are called embryotoxic.
Teratogenic factors in embryology.
1. Physical factors.
a) radiation exposure. Ionizing radiation does not produce a specific set of defects; however, most often in such cases defects of the nervous system and skull are observed.
b) mechanical impact. Incorrect formation of fetal organs is possible (congenital amputations of fingers or toes, fusion of individual organs, etc. occur). In some cases, fetal death may occur.
2. Chemical factors.
Literature data on the significance of one or another chemical factor in the origin of EP are extremely contradictory and sometimes clearly erroneous.
The reasons for such errors are mainly related to the retrospective nature of the study, the lack of adequate control and the high possibility of combining the birth of a child with CAP and exposure of a pregnant woman to various chemicals. All researchers agree that new chemical substances, including medications that have been tested on animals, should not be prescribed to pregnant women before clinical testing for teratogenicity.
But if the use of medications is necessary, then the chemical structure of the substance, its ability to overcome the placental barrier, the total and single dose of the substance introduced into the pregnant woman’s body, and the rate of distribution of the substance should be taken into account.
The dose of the substance is of great importance. It is also important how the medication is administered: in fractional doses and repeatedly or in a short period of time, a “load” dose of the drug is received. The fact is that some drugs, when used chronically, stimulate the production of metabolic enzymes, as a result of which these drugs are quickly eliminated from the body and do not reach a concentration at which a teratogenic effect is possible. For some hormones, an inverse relationship is known: long-term use of small doses produces a greater teratogenic effect than a single total dose.
Teratogenic effect of drugs.
Of the group of tranquilizers, teratogenic activity on human embryos has been proven only for thalidomide and diazepam. Thalidomide is a drug of low toxicity for an adult organism, when introduced into the body of a pregnant woman, it leads to disturbances in the structure of the upper and lower extremities of the fetus, to abnormalities of the external ear and eyes. Disorders of internal organs are rare; defects are observed more often than others gastrointestinal tract, heart and kidneys.
Diazepam significantly increases the incidence of births of children with cleft lip and palate.
Teratogens include some anticonvulsants that lead to a deficiency of folic acid in the body, which is actively involved in the synthesis of nucleic acids and nucleotides.
In the case of taking warfarin, children experienced disturbances in the structure of the nose, changes in the structure of the optic nerves, and developmental delay.
Chemicals used in everyday life and industry. The greatest interest of researchers was attracted alcohol.
The significance of maternal chronic alcoholism in the origin of congenital defects has been pointed out for a long time. Back in 1959, L.A. Bogdanovich wrote that in women who chronically drink alcohol, children are born premature in 34.5% of cases, physically weakened in 19% of cases, and VP development is observed in 3% of cases. In such cases, children are born with a deficiency of height, body weight, general retardation of physical and mental development. Frequent involvement of the central nervous system was observed. Heart and kidney defects are common.
Causality smoking with congenital defects has not been established, however, it is known that the body weight of newborns in smoking mothers is lower than in non-smoking mothers, rupture of the membranes and premature placental abruption are more common. This is all explained by the direct effect of nicotine on the mother's blood vessels and changes in the composition of the mother's blood.
Widely used in industry and agriculture, gasoline, benzene, phenols, nitrogen oxide, many pesticides, as well as lead and mercury vapor have embryotoxic properties. Exposure to them can cause fetal death or the birth of a weakened child.
Drugs. Substances of different chemical groups have different effects on the mother’s body, and as a result, on the fetus. Opiates (morphine, which is prohibited for use, heroin) have a mosaic effect (some centers are activated, others are inhibited). Cocaine and cannabis preparations cause hallucinations. When morphine and its analogues are administered, the respiratory center is severely depressed, and death from respiratory arrest is not uncommon.
From the first moments of life to the very last minute, the human body interacts with the external environment. This interaction is a necessary condition for normal height and human development.
Under the influence of almost any influence, changes in the internal environment of the body occur to a greater or lesser extent, and all its known reactions are aimed at maintaining or equalizing its parameters. They are called adaptive-compensatory reactions(adaptation- from lat. adaptation, habituation), which are based on adaptive-compensatory mechanisms. If the intensity or aggressiveness of the factor does not go beyond the limits of adaptive-compensatory reactions, the body copes without much damage. With prolonged exposure, these mechanisms are destroyed and the disease develops.
External environment as an integral system includes large number various elements or factors that differ from each other in quantitative and qualitative terms.
Physical factors. TO physical factors include all types electromagnetic vibrations natural or artificial origin.
The most powerful natural source of electromagnetic vibrations in nature is the Sun. It is thanks to solar energy that all biological processes on Earth occur. The wavelength range of solar radiation extends from a few fractions of a nm (gamma radiation) to meter-long radio waves.
Of all solar radiation in the visible range, the strongest biological effect is ultraviolet radiation. It has a pronounced erythemal effect, i.e. it causes redness of human skin with subsequent formation of pigment. This is nothing more than a protective reaction of the body from overheating. Thus, direct exposure to ultraviolet radiation on a living organism is far from safe.
Natural natural sources of EMF can be divided into two groups. The first includes constant Earth's electric and magnetic fields, to the second - radio waves, generated by cosmic sources (Sun, stars), as well as electrical processes in the atmosphere, such as lightning strikes. The frequency range varies widely.
Different people react differently to EMFs, as they have different sensitivity to them. Some people do not notice magnetic storms at all, while others, on the contrary, feel even minor changes in electromagnetic fields.
Artificial sources electromagnetic radiation are radio stations, radar stations, high-voltage power lines and many others transmitting technical means. They emit energy in a very wide range of wavelengths - from millimeters to several tens and hundreds of meters. Particularly strong effects are observed near radiation sources.
Chemical factors. Chemicals are widely used by humans in production and in everyday life (preservatives, washing, cleaning, disinfectants, as well as products for painting and gluing various objects).
All chemicals used in everyday life, in small quantities are safe for health. However, violating the rules for their use can have an adverse effect on the body.
Chemicals should also include medicines, which are prescribed by doctors for various diseases. Many modern medicines come in the form of multi-colored dragees and have a very attractive appearance, so children often confuse them with candies. Meanwhile, one tablet is enough to cause serious poisoning in a child, life-threatening.
Biological factors. The forms of existence of living matter on Earth are extremely diverse: from single-celled protozoa to highly organized biological organisms. All known microorganisms can be divided into three groups: completely safe for humans(saprophytes), we are constantly in contact with them, but this never causes diseases; definitely harmful that is, dangerous to human health (meeting with them is always fraught with the development of an infectious disease, however, this happens when the body does not have appropriate protection); conditionally pathogenic(these are microorganisms that under normal conditions do not cause any diseases in humans, however, when the body is weakened due to a cold or chronic disease, malnutrition, vitamin deficiency, stress, fatigue, etc., they can cause diseases). Group selected especially dangerous microorganisms that cause severe diseases in humans. These are, for example, the causative agents of smallpox, plague, cholera, tularemia, anthrax, and polio.
Social factors. Social factors are associated with people's lives, with their attitude towards each other and towards society. Revolutionary changes almost always cause social tension in society, which can have a negative impact on the individual and society as a whole. And on the contrary, the calm, progressive, evolutionary development of society and social relations guarantees a calm, creative environment and a reduction in the influence of factors of social nature on human health.
Mental factors. Environmental factors that have a mental connotation are associated with a specific aspect of human life. A person’s behavior in various situations, his perception of the surrounding reality, its emotional coloring, the nature of a person’s behavior in a given situation, the formation of his personality are closely related to factors of the external and internal environment and their interaction with each other.
The implementation of the ideas of mental and social health will require each person to rethink such personal qualities as activity and responsibility, and for society to reconsider established priorities and traditions in the field of upbringing and education, work and leisure.
Critical periods of development. One of the main patterns of development is heterochrony - the formation of organ anlages at different times and the different intensity of their development.
The first critical period is at the beginning or in the middle of crushing;
The second is at the beginning of gastrulation;
The third coincides with the formation of the rudiments of all organs.
Implantation (6-7 days after conception)
Placentation (end of 2 weeks of pregnancy)
Perinatal (childbirth)
At these stages, the embryo is especially sensitive to a lack of oxygen, high or low temperature, mechanical stress, etc. During critical periods, the embryo's metabolism changes greatly, respiration increases sharply, the RNA content changes, and new, previously absent proteins are immunologically detected. At the same time, the growth rate is falling. Critical periods coincide with active morphological differentiation, with the transition from one period of development to another, with a change in the conditions of existence of the embryo. (transition of the zygote to fragmentation, the onset of gastrulation, implantation of the blastocyst into the uterine wall (in mammals)). The critical period in the newborn’s body is associated with a sharp change in living conditions and restructuring in the activities of all body systems.
Teratogenesis- the occurrence of malformations under the influence of environmental factors (teratogenic factors) or as a result of hereditary diseases.
Teratogenic factors include medicines, drugs and many other substances. The effect of teratogenic factors is dose-dependent. The dose dependence of teratogenic effects may vary among different species. For each teratogenic factor there is a certain threshold dose of teratogenic action. Usually it is 1-3 orders of magnitude lower than lethal. Differences in teratogenic effects in different biological species, as well as in different representatives of the same species, are associated with the characteristics of absorption, metabolism, and the ability of the substance to spread in the body and penetrate the placenta. Sensitivity to various teratogenic factors may change during fetal development. In cases where infectious agents have a teratogenic effect, the threshold dose and dose-dependent nature of the action of the teratogenic factor cannot be assessed.
Major developmental defects
Malformations of the central nervous system
Malformations of the central nervous system are classified as polygenic diseases.
