The chance of live birth following assisted reproduction is significantly reduced when the prospective father is over the age of 50, a recent study has revealed. 

Despite the belief that male fertility is not subject to a biological clock, a group of researchers at the Centre for Reproductive and Genetic Health in London found that when the father is over the age of 50 the likelihood of a live birth following IVF or ICSI is 33 percent lower than for men under the age of 50. The rates of miscarriage remain unchanged, a finding which is echoed among other similar studies.  

'Paternal age over 50 significantly affects the chance of achieving a live birth following assisted reproductive technology. There should be a public health message for men to not delay fatherhood', the authors wrote.

The findings were originally revealed at the European Society of Human Reproduction and Embryology in 2019, and were published in the journal Acta Obstericia et Gyneologica Scandinavica this month. Data was taken retrospectively from nearly 4300 adults who had undergone IVF or ICSI using fresh sperm and embryo transfer at a single London fertility clinic. This report comes amid a growing trend of men fathering children much later in life. Dr Guy Morris, lead author of the study, said in the Daily Mail that publicised stories of male celebrities over 60 still having children has helped to fuel the incorrect belief that 'male fertility lasts forever'. 

The age-related decline in fertility amongst women is well-documented. Interestingly, the analysis of this data showed that the decline in live births occurred irrespective of female age. This is a particularly important finding as it underlines the previously unknown significance of male age when fathering children. 

This study included males affected by all forms of infertility, thereby improving the validity of these findings, and making them applicable to all couples. Furthermore, the researchers considered additional variables such as semen quality and the method of fertilisation, yet still found that male age negatively impacted fertility independent of the variation in these factors.  

However, several lifestyle factors, including smoking, body mass index and alcohol consumption, could not be controlled. It is plausible that these factors may also negatively influence fertility amongst males. The study did go on to report a lower level of sperm quality amongst males over 50 when compared to those of a younger age. This may begin to explain the decline in fertility, however the mechanisms through which this could occur are yet to be characterised. 

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Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.