Teenage fathers were the subject of scrutiny last week after a report in the journal Proceedings of the Royal Society B suggested that the rate of sperm mutation is higher in young men aged 15 to 19.9 than it is in young men aged 20 to 24.9.
Although the findings of the report did generate some useful data about the frequency of cell divisions (that the rate of mutations in sperm is around six times higher than it is in eggs, which shows that sperm cells go through more cell divisions than eggs), both the authors of the report and a number of newspapers used the results to create sensationalist headlines, subtly provoking a debate about the morality of fathering children during our late teens.
Unsurprisingly, the report makes no reference to a number of other potential contributory factors, such as smoking, drinking, drugs and socioeconomic status, all of which could have an effect on sperm production and mutation in teenage men. A similar US study (highlighted by BioNews) revealed that the risk of birth defects in children fathered by men under the age of 20 was only 3% higher than in children fathered by men aged 25 to 29, which corresponds with the 2% abnormality risk quoted by Dr Peter Forster, a Fellow at the University of Cambridge who was part of the team that conducted the new study.
This 2% abnormality risk for teenage fathers (quoted in the new Royal Society report) is just 0.5% greater than the 1.5% abnormality risk considered to be the general average for all fathers of reasonable age. This is not a statistically significant difference and pours scorn on one tabloid headline that made reference to a ‘30% higher mutation risk’. The 30% figure actually refers to the 30% higher rates of sperm cell DNA mutation in young men in their teens, compared to young men in their twenties, and this figure is soon put into context when compared to the rates of sperm cell DNA mutation in men in their late thirties and forties, which are on par with the rates for young men in their teens.
Whatever your opinion of teenage pregnancies, there is little doubt that this kind of reporting does valuable fertility research few favours in the long term.