Fathers of test-tube babies may be passing on their infertility to their sons, scientists have discovered.
In a new Anglo-German study, which compared 211 six-year-olds conceived through ICSI (intracytoplasmic sperm injection) with 195 naturally conceived children of the same age, doctors uncovered that boys conceived through IVF treatment involving a single sperm being directly injected into a female egg often inherit shorter fingers, a trait known to be associated with infertility.
ICSI bypasses the normal competition where only the healthiest sperm cell is able to reach the female egg and fertilise it.
Alastair Sutcliffe, a paediatrician at the Institute of Child Health in London, led the study, reports The Times.
The study has been published in the journal Reproductive Biomedicine Online.
"This is the first study of this kind on these children," Sutcliffe said. "We don't yet know the implication of the findings because the children are very young, but we need to inform people [about the possible risks of the ICSI procedure]."
"This [research] is telling us that we should only use ICSI when it is absolutely necessary," said John Manning, an evolutionary biologist at Southampton University who has examined the link between finger length and fertility and who is one of the authors of the latest study.
"We know the extraordinary depression and pain that childlessness can cause and we have a responsibility to ensure that the focus on the wellbeing of the children born as a result of these techniques is as high as it can be."