The latest is the review published in the American Journal of Stem Cells and edited by a group of researchers from Georgetown University. According to the authors of the study, from the epidemiological data analyzed would emerge a link between age, diet, psychophysical stress and alcohol consumption by the father before conception and the increased risk for children of schizophrenia, birth defects, autism, metabolic dysfunction and cardiovascular disease.
How can the lifestyle of the future father affect the health of the child? What weight does it have compared to the maternal weight? And what useful advice can be obtained for men?
Between genetics and the environment
A diabetic or obese father probably has a genetic predisposition to develop metabolic changes: insulin resistance, hypercholesterolemia, dyslipidemia. It is therefore possible that it transmits the same characteristics to the child. And nothing can be done about this.
But the genetic make-up is not everything. “The environment in which gametes are formed, i.e. the oocytes in women and sperm in men, influences the activation or silencing of their genes,” explains gynecologist Irene Cetin, a member of the scientific committee of ASM, the Association for the Study of Malformations. “These mechanisms, called epigenetic mechanisms, can compensate for the predisposition to a disease or, on the contrary, make it emerge. Therefore, by regulating the diet, avoiding harmful habits and behaviours, one can actively influence the information that the gamete transmits to the embryo and condition its development. A man genetically predisposed to obesity, who however keeps it under control by adopting correct eating habits, can transmit to his son an amended version of his DNA. To what extent is this correction possible? In the current state of research, we are not in a position to establish this.
Does the mother or father count more?
It is clear, therefore, that the future fathers share the responsibility of mothers for the health of the unborn child. But in what proportion? Does the influence of the father or the mother weigh more?
“Since the genetic patrimony of the embryo derives 50% from the mother and 50% from the father, the influence of the two parents at conception is equal”, replies the gynaecologist. “Later, however, the embryo is formed and grows in the mother’s body. That is the environment that influences its prenatal development, the activation or silencing of certain genes during the nine months. In the end, therefore, the maternal lifestyle is more decisive than the paternal one”.
The epigenetic effects of the paternal lifestyle is a young area of research. The studies completed so far are limited in time. “We cannot say that the poor diet of the father before conception is related to a greater risk of obesity of the child in adulthood, because the children under study have not yet reached adulthood,” explains Cetin. “Only short-term effects have been verified, for example on birth weight, on the frequency of birth defects or on the presence of certain substances in the blood of the cord. Other studies tell us that these signals are in turn related to disorders and increased risk of disease in adulthood. For the time being, however, we do not have direct evaluations.
How much does age weigh
It has long been known that advanced maternal age at conception is a risk factor for chromosomal abnormalities such as Down’s syndrome and other diseases. It seems that the risk also increases in proportion to paternal age at conception. “Aging is detrimental to the genetic quality of sperm”, explains Cetin, “which can present imperfections, the more likely the more the man is ahead with the years, and transmit these alterations to the embryo at the time of conception”.
Researchers at Georgetown have shown a correlation between advanced paternal age and birth defects in children, autism and schizophrenia.
More vitamins and minerals at the table
“Diet is a powerful epigenetic factor,” says Irene Cetin. “We’ve known this for a long time now and new evidence is constantly emerging. We know, for example, that a diet rich in vitamins and minerals creates a more suitable environment for the proper development of spermatozoa and limits the risk of chromosomal alterations. In recent years, the quality of food in industrialised countries has deteriorated. We are gradually moving away from the healthy model of the Mediterranean diet and according to some specialists this trend is related to an increase in the frequency of miscarriages in the first weeks of pregnancy.
The maternal diet during the waiting period can give the unborn child a sort of metabolic imprinting. According to the Georgetown University study, paternal feeding before conception would have a similar role.
Cigarettes: they hurt him, they hurt the fetus
“Think of a man who smoked before conception,” says Irene Cetin. “Once the pregnancy has started, he continues to smoke and so does after the birth, exposing his pregnant partner and then the newborn to the risks of passive smoking. To what extent is any damage to the child’s health due to the epigenetic effects of paternal smoking before conception and to what extent is it due to passive smoking in the following months? A study published some time ago looked at a group of children of non-smoking women and smoking men whose conception was the result of an occasional relationship. Mothers and subsequently children had no contact with fathers, so they were not exposed to the risks of passive smoking during pregnancy and after birth. Yet, at the time of delivery, umbilical cord blood analysis revealed the presence of some chemical markers typical of children of smokers. It therefore seems proven that paternal smoking before conception has an epigenetic effect on the development of the unborn child. We still do not know to what extent.