[Fertility of the aging male]

Abstract

Although the effect of ageing on female fertility has been well documented, the reproductive functions of ageing males have been less extensively investigated. Unlike females, males do not experience a sudden arrest of gonadal endocrine and exocrine functions characteristic of menopausal ovarian deficiency. It therefore appeared useful to review the course of male fertility with age and the genetic consequences for children related to paternal ageing. The most recent histological and endocrine examinations demonstrate progressive alterations of testicular endocrine and exocrine function with ageing. Deterioration of male fertility with ageing can also be demonstrated by studying semen parameters. A review of the literature presented in this article demonstrates a decline in semen volume and a reduction of sperm mobility and the percentage of normal forms. The age-related variations of sperm concentration is more controversial. The study of the fertilizing property of spermatozoa raises difficult methodological problems. Under conditions of natural reproduction, the other factors of the couple's fertility (the spouse's age, declining frequency of sexual intercourse, etc.) constitute confounding factors and may introduce a bias in the analysis. However, epidemiologically, there is a strong correlation between the age of spouses. The study of male fertility in medically assisted procreation is more clearly documented. The various published series clearly demonstrate a reduction of the results with increasing paternal age. Age-related deterioration of male fertility is also associated with an increased genetic risk for the offspring, especially an increased risk of chromosomal aberrations and autosomal dominant mutations responsible for various malformations or functional disturbances and an increased risk of sex-linked recessive mutations.