From here to paternity: older fathers and sperm donation

Dr Allan Pacey, Senior Lecturer in Andrology, University of Sheffield

Progress Educational Trust

28 July 2005

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[BioNews, London]

The eighth child of Charlie Chaplin was born when he was 73 and as far as we know has lived a healthy life. However, whilst most men remain fertile into their old age, it has long been recognised that to father children later in life increases the risk of their being born with a variety of conditions such as Down syndrome, achondroplasia and even schizophrenia. Therefore, the recent report published by Danish scientists showing that increased paternal age is linked to a greater risk of some congenital malformations (as well as Down Syndrome) is perhaps not surprising.

What makes the study interesting is that the conclusions are derived from an analysis of nearly 72,000 singleton birth records taken from the Danish Fertility Database. With such large numbers it is possible to adequately control for the known risks of female age and therefore look at the children fathered by older men whose partners were between the ages of 20 and 29. The conclusions were striking: the risk of some conditions rose significantly in fathers as young as 35 and by the time a father is over 50, the risk of Down syndrome had increased fivefold above that seen in fathers aged 20-29.

So why should this be of interest to anyone other than male celebrities who find that they have managed to snap up a younger bride? Well, we at fertility clinics are now being encouraged to preferentially recruit as sperm donors, men who have completed their own families and who apparently better appreciate the joys of children and the responsibilities of being a father. However, data from the Office for National Statistics suggests that the age at which men are choosing to be fathers is increasing and in 2003 a third of all UK births were in men older than 35. This, in combination with the fact that current guidelines for the recruitment and screening of sperm donors recommend that they be no older than 39 (because of the risk of age related new mutations in the male germ line that this Danish study confirms), means that our pool of candidate sperm donors may be much smaller than we have previously realised.

We have no choice about what age our parents choose to reproduce and what legacy that decision may have for our own genetic health. But in a medical setting, when donor gametes are being used, we have a duty to minimise risk both to the patient (of acquiring infection or disease from the donor) and any donor-conceived person (of inheriting a serious genetic disease). Political and social pressure to increase the upper age limit for sperm donation - as an easy way of increasing the supply of suitable donors - should be resisted at all costs because it does not logically follow that the removal of donor anonymity allows us to increase the level of risk to patients and donor conceived people. However, studies like this are extremely helpful in reviewing the current recruitment guidelines to see if they are still appropriate and adequately supported by evidence.