Introduction

While the adverse effects of maternal age on reproduction are well documented and evident, reproductive effects related to advanced paternal age are less well defined. According to the Office for National Statistics, in 1971 the mean age of a father at birth was 27.2 years but by 1999 this had risen to 30.1 years and by 2004 it had risen to 32 years. In the UK in 2004, more than 75 000 babies, that is, more than one in ten of all born, were born to fathers aged 40 years or over and 6489 children were born to fathers aged 50 years or over. In recent years, male reproductive ageing has come into view, mainly in the lay press. However, few well-designed studies have been conducted on this subject and major textbooks on andrology only cover the endocrine aspects of male ageing but not its reproductive effects.

Studies referring to ‘testicular reserve’ in men focus on the endocrine function, that is, androgen production. With ageing, testicular androgen output declines. This condition has been named andropause, partial androgen deficiency in the ageing male and testosterone deficiency syndrome, among others, but it is now currently referred to as late-onset hypogonadism. Late-onset hypogonadism is defined as a clinical and biochemical syndrome associated with a deficiency in testosterone because of advanced age and is marked by a progressive development of osteoporosis, mood disorders and metabolic changes.