Age and male fertility: biological factors

Although the effect of maternal age on fertility is well known, whether paternal age also affects fertility remains unclear. If there is an effect, the biological causes and consequences, especially for the offspring, are unclear. We present a short review of the data and various studies on this subject. Data on young men or fathers are not considered here. Advanced male age has been associated with: - Increased time-to-pregnancy (TTP) and subfecundity; - low semen volume, total sperm count, sperm motility and normal sperm morphology; - gradual modification of testicular vascularisation and regular decrease in the number of Sertoli and Leydig cells, with an associated decrease in serum testosterone. There are wide interindividual variations of these modifications, with some elderly men having a reproductive function similar to young men. Whether there is an increase in levels of qualitative and or quantitative alterations of the sperm chromosomes with advancing age remains controversial. It can be suggested that there is an increased risk of developmental defects in the offspring of older men, as the spontaneous mutation rate is closely related to the age of the man. An increasing rate of miscarriages has been related to older fathers and several studies suggest older fathers are at the origin of several diseases in the new-born. In. conclusion, further studies are needed due to the increasing number of older men wishing to become a father.