Thousands of boys born each year using a common fertility technique could be inheriting their father’s infertility, researchers have found.
Intra-cytoplasmic sperm injection – known as ICSI – is used in more than half of all fertility treatments in the UK, with some 9,000 babies born each year as a result.Tests on the first group of men to have been born using ICSI have now shown that they too suffer from low sperm counts and poor-moving sperm.
Researchers said a ‘degree of sub-fertility’ had been passed on to them from fathers unable to conceive naturally.ICSI involves injecting the sperm directly into the egg. A normal cycle of IVF follows, with embryos being transferred to the womb.
The study was conducted by the Belgian pioneers of ICSI, on 54 men who had been born in the first years of the technique between 1992 and 1996.The participants, all aged between 18 and 22, agreed to have their sperm tested. The samples were compared with those of 57 men of a similar age, who had been conceived naturally. The results, published in the journal Human Reproduction, show that men conceived via ICSI had half the sperm count and half the number of well-moving sperm, compared with men conceived naturally.
The study, led by the Centre for Reproductive Medicine at the Vrije Universiteit Brussels, also showed that men born from ICSI were almost three times more likely to have sperm concentrations below 15 million per millilitre of semen, the World Health Organisation’s definition of healthy semen.
Study leader Professor Andre Van Steirteghem said his team had always known that the problems that had caused the father’s infertility, usually genetic factors, might be inherited by their sons.These first results indicate that a degree of “sub-fertility” has, indeed, been passed on to sons of fathers who underwent ICSI because of impaired semen characteristics.’
But Professor Van Steirteghem said even though the sons had lower sperm counts and sperm that moved less well, the results did not exactly match those of their fathers.‘The study shows that semen characteristics of ICSI fathers do not predict semen values in their sons,’ he said. ‘It is well established that genetic factors play a role in male infertility, but many other factors may also interfere.’
Professor Richard Sharpe, who leads the male reproductive health research team said: ‘The results suggest strongly that male fertility problems severe enough to require ICSI may be inheritable. The results are a reminder to us that ICSI is not a treatment for male infertility, but simply a way of bypassing a problem and leaving it for the next generation to deal with.’
Professor Allan Pacey, a Sheffield University fertility expert, said that although men born with ICSI had lower sperm counts, many will still be able to conceive naturally.‘It doesn’t automatically follow that ICSI-conceived males will always have the poor fertility seen by their fathers,’ he said. ‘Although the study only looked at a relatively small number of 54 men, I see this as quite reassuring.’