A seventh child for Robert De Niro at 79, a fourth to come for Al Pacino at 83. If the little music of the biological clock quickly begins its ritornello in the female ears, it seems to forget the men. Really ? Over the years, the average age of the father at the time of the first child shifts slowly, from 27.4 years in 1974 to 30.9 years in 2015. Uncertain economic climate, longer studies, housing difficulties… many factors explain why the child project is postponed for several years.
One certainty: female fertility declines rapidly with age. It peaks between the ages of 20 and 30 and then gradually decreases and drops from the age of 40. Biologically, a woman experiences natural menopause between the ages of 45 and 55, thus marking the end of her reproductive life. What about men?
From the age of 40, the production of spermatozoa is reduced and, even if there are still some, their quality decreases. Specifically, the genome of spermatozoa is altered by fragmentation of its DNA. “The sperm are less valiant and their mobility is diminished. If all men wanted a child at the age of 70, there would be a lower chance of conception success,” explains the epidemiologist.
What are the medical consequences of late paternity? Few studies have been conducted on the relationship between the age of the father and the occurrence of certain medical problems. Some, however, mention an increased risk of miscarriage, premature delivery or intrauterine growth retardation. “As the sperm is of poorer quality, it can cause genetic alterations incompatible with a viable fetus”, explains Luc Multigner.
Concerning the health of the child, studies describe an increase in the cases of certain genetic diseases. “You can see an increased risk of rare diseases. For example, the risk of retinoblastoma [malignant tumor mainly affecting infants and young children, editor’s note] is higher, as well as that of achondroplasia [constitutional bone disease causing dwarfism, editor’s note]. The risk of trisomy 21 is also greater, it goes from one birth in 1,200 to one in 900, “adds the research director at Inserm.
Some studies link late fatherhood to a child’s risk of developing autism spectrum disorders. “The scientific community is not unanimous on this. We must also take into account the family environment in the occurrence of these disorders, “says Luc Multigner.
A review of the literature published in 2015 reports that “increasing paternal age is more frequently associated with an increased incidence of different types of disorders such as autism, schizophrenia, bipolar disorders and childhood leukemia in offspring”.
Recently, on May 17, 2023, a cohort study was conducted with 18 million births. It reveals that men over 44 were more likely to have babies with birth defects. “Advanced paternal age increases the risk of birth defects, particularly chromosomal abnormalities in their offspring, implying the need for prenatal genetic counseling,” the study points out. But Luc Multigner nuance: “Even if the risk increases, there is still more chance of having a healthy child than affected by a genetic disease. »