The man’s age and infertility
The father’s age has an impact on fertility.
Men produce sperm cells throughout their whole life, but with the pass of time, changes in the spermiogram and sperm cell oxidation may happen, subsequently reducing the fertilizing capacity of semen. Furthermore, the possibility of having the genetic material in spermatozoids damaged is increased with age, which may originate an illness in one’s offspring.
The importance of the age in which one has a child is well-known in females but not as taken into account in men. Nevertheless, men too have a biological clock going on.
The male reproductive organ’s physiological aging is expressed in three different aspects:
- The spermiogram shows a slow though progressive reduction in seminal volume (0.03 ml/year). This is due to the ongoing aging of the seminal vesicles, which produce a liquid that acts as a vehicle for the sperm cells generated in the testicle.
- The percentage of sperm cells with top mobility is reduced (approximately 0.7%/year).
According to a population study carried out by Institut Marquès in which tree different age ranges were analyzed (18 – 30, 31 – 45, and 46 – 65),there is no difference found in sperm cell concentration, total percentage of mobility, or morphology.
- Time may oxidate and cause injuries in the sperm cells’ DNA chain.
Male’s age and his offsprings’ illnesses
The father’s age is associated to a higher alteration rate on the sperm cells’ chromosomes and to new mutations that may appear in his offspring, such as infertility, miscarriages, illnesses, or congenital malformations. Thus, the risk of having a spontaneous mutation in a gene is 4 times higher with a 45 year old father than with a 20 year old one.
An advanced father’s age is related to the following pathologies:
A) Chromosomal anomalies. About 10% of Down Syndromes and up to 40% of Klinefelter “de novo” Syndromes are associated to fathers over 55.
B) Achondroplastic dwarfism, newfound neurofibromatosis cases, tuberous sclerosis, Marfan, Apert Syndrome, aniridia, and bilateral retinoblastoma.
C) Other pathologies such as schizophrenia and autism. Late parenthood, both mother or father, increases the risk of having an autist child: probability increases an 18% every 5 years.
When a man has a child far into his lifetime, even his grandchildren have a higher risk of suffering from some anomalies that may not have shown in the middle generation: Duchenne muscular dystrophia, fragile X syndrome, and some kinds of hemophilia.
A mutation is a change in a gene’s information. A person has 23 pairs of chromosomes, each containing a determined amount of genes. Each gene is responsible for a certain physical trait or for the function of an organism. For example, a specific gene determines skin color while another is in charge of the amount of hair in every body part, etc.
Genetic mutations are necessary for a specie’s evolution, since it needs to adapt to its environment. For example, dark skin color suits a hot environment.
Nevertheless, nature can also make mistakes. An anomalous mutation can take place in a group of cells and develop into a tumor. Also, a mutation may appear in the reproductive cells and lead on to the birth of children that suffer from a hereditary illness.
Achondroplastic dwarfism may be taken as an example: the mutation affects one of the growth-responsible genes. It may be hereditary, since 50% of an affected person’s children will suffer from this same illness. Regardless, it may also be a “de novo” mutation and appear despite a lack of any precedent family cases.
Sperm cell mutations
Spermatogonial cells, a sperm cell’s previous state, get multiplied in fetal life, then stop, and from puberty on start multiplying again, non-stop, until death.
During the sexually active stage, their multiplication rate is of approximately 23 per year. Thus, for example, a 38 year old’s sperm cells have undergone approximately 540 divisions, which are about 800 for a 50 year old man.
In the cellular multiplication phases there is a risk of possible mutations taking place. In other words, a pathogenic external agent may lead to certain DNA errors. The risk increases with a greater number of undergone divisions, which are directly related to a man’s age.
Mutations due to inducting external agents
- Ionizing radiations.
- Chemical agents. For example, lead affects cast-iron workers, welders, battery manufacturers, etc., whose children have a higher risk of suffering a mutation during their neurological development. Also, mercury contained by amalgams affects dental prosthesis manufacturers, while cadmium affects men through tobacco, dirt, diet or contaminated water. Organic solvents also have an effect on painters, printers, typographers, mechanics, carpenters, welders, etc.
- Environmental toxic agents.
Man’s age and In Vitro Fertilisation
The average age of the last 10.000 males who underwent an IVF treatment in Institut Marquès is of 41,8.
There is a positive correlation between both members in a couple: the man’s age is usually proportionally higher to the woman’s.
Semen quality is genetically determined
Each person has a different degree of fertility. Apparently, it depends on the masculine chromosome, which is inherited from the father. This is, if the toxic elements located in the mother’s body fat don’t interfere during the fetus’ testicular development.
What can we do about it?
Preimplantational Genetic Diagnose (genetic analysis of the embryos) and Prenatal Diagnosis (Amniocentesis or corion biopsy and high-level ecography) should be applied if the progenitor’s age is higher than 50.