The desire to have offspring, as a law of nature, is ascribed to every species living on earth and each individual seeks to pass on its genes and maintain the continuity of its species. The human species is not isolated, but it is the female of the human race - the woman - who is subject to a process that is atypical of the laws of nature, namely the menopause, which involves the extinction of the ability to reproduce and is inherent in the biological nature of every woman. From a statistical point of view, as a woman gets older, the risk of birth defects in the child she is trying for also increases.
Table of contents:
- Errors in the course of conception
- Menopause
- Critical time for pregnancy
- Selection
- Looking to the future
From a biological point of view, the purpose of every individual's life is reproduction - to give birth to offspring and to ensure the survival and spread of one's own genes. Everyone strives to reproduce, to ensure it to the maximum and optimum, a fundamental law of evolution that characterises all species on earth.
Sometimes, however, certain abnormalities occur during the fertilisation process, resulting in conditions pathological enough to develop various types of birth defects. In the human population, major congenital anomalies, the effects of which are a significant limitation of the ability to function independently, occur in approximately 3% of cases, of which 1/3 of births may have a disorder severe enough to result in an immediate threat to life.
In addition to major congenital malformations, about 15% of cases are so-called malformations, which do not pose an immediate threat to the life of the newly born child. The causes of congenital malformations have been the subject of research by scientists for many years and it is believed that in 85 per cent of cases, they are caused by genetic factors, in six per cent by chromosome aberrations and in about seven per cent by mutations in the genotype. The remaining cases of birth defects are attributed to infections during pregnancy or exposure to drugs, alcohol or radiation agents.
Errors during conception
Contrary to popular belief, errors in the course of fertil isation can be a very common cause of fetal malformations. According to observations, up to 90 per cent of abnormal embryos or fetuses with abnormalities die spontaneously causing miscarriage. This usually has no negative consequences for the woman and does not jeopardise her health or the prognosis of her next pregnancy attempt. However, the mechanisms governing this process are not clinically clear, which does not change the fact that it is largely responsible for the evolution of our species.
Menopause
Menopause is a phenomenon that occurs in the course of natural biological processes in women, which is specific only to the human species, as this phenomenon is not observed in nature in other female mammals. Menopause is the cessation of ovarian function, i.e. the cessation of fertility function - the loss of the ability to get pregnant and have children. Underlying the link between fetal abnormalities and maternal age, is the abnormal course of the process of gemetogenesis itself in women [1], a process during which a special type of cell, known as gemet or, in other words, germ cells, is produced [2]. In the course of gemetogenesis, cells of the genital pathway are formed, which, after reaching sexual maturity, will develop into cells capable of fertilisation. However, they are formed at a very early stage and do not have the opportunity to multiply in the postnatal period. As a result of natural and genetically determined cell death, there is a steady decline in the number of primary sex cells. Menopause is therefore the result of a depletion of the supply of these cells in a woman's body.
The model in question - the course of primary germ cell production and fertility in women - provides a sound basis for explaining the relationship between a woman's age and the likelihood of a child being born with a malformation.
Critical time for pregnancy
Statistics reveal a regularity - women who become pregnant at a later age are more likely to have problems with abnormalities in the course of pregnancy and the birth itself. It is also more common for these women to give birth to offspring with symptoms of severe illnesses. The critical period, from a clinical point of view, for getting pregnant is after the age of 35.
This fact may be dictated by genetics, but on the other hand, it is worth noting that potential reproductive cells remain dormant for a much longer period of their lives without undergoing the dynamics of cell division, during which selection takes place for regularities (or abnormalities) in the genetic record they retain. In addition, they are subject to the action of adverse factors, such as biochemical substances or mutagenic environmental factors, which induce gene mutations in the cells. Random gene mutations in cells accumulate, a process we call ageing. The result of such a condition, is an increased likelihood of genetic abnormalities as a woman ages. All accumulated mutations, therefore, can have a significant impact on the development of the embryos that will be obtained after fertilisation of the oocytes.
The fertilisation process, photo: panthermedia
Selection
In addition to the statistics that clearly explain the relationship between a woman's age and the increased number of birth defects in the foetus, it is also worth noting the selection process that takes place in each cell. This process is characterised by randomness - the mother's body, during pregnancy, is capable of eliminating abnormally developing foetuses. The efficiency of this process is very high and covers the vast majority of developmental disorders. However, recent years have brought a new perspective on this process, namely - the ageing process is taken into account. The basis for elimination measures here is a disturbance in communication between mother and foetus. This disruption is also based on natural processes, as the female organism, at a certain age, naturally prepares itself for the cessation of its reproductive functions and capacities, which in turn means that it gradually increases its tolerance to pathological changes (including changes in the embryo). This concept has also been given its own name, which in relation to the background is referred to as the 'closing door effect'.
A glimpse into the future
Scientists are looking anxiously into the future of our population. Societies are changing more and more, linked to the development of technology, but also to the socio-economic development of individual environments. Lifestyles are changing and many times so is the quality of life. All this is leading to an increasing disconnection between man and the laws of nature, which is evident in the developments that have taken place, for example, in medical technology and in the care of the sick. The level of medical care is increasing and so is the general trend, but this is accompanied by a worsening of the genotype through the accumulation of gene mutations, associated with a prolonged survival rate.
Saving newborns, even with the most severe malformations, is a success story for science and knowledge and is absolutely right. However, this does not change the fact that unfavourable genes - mutated genes - are promoted as a consequence. Already today, the phenomenon of delaying the age of maternity can be observed, which is largely dictated by changing lifestyles and lifestyles, but also by significant advances in medicine that assist women in becoming pregnant and in carrying out the entire pregnancy safely [1].
