Researchers from Italy have shown that infertile men can more than double their chances of fatherhood with a new IVF technique called intra-cytoplasmic morphologically-selected sperm injection (IMSI).

The method, which was first developed in 2004 by a team led by Benjamin Bartoov, of BarIlan University in Israel, involves examining sperm under a high-magnification microscope, about five times more powerful than standard laboratory equipment, to select those with a shape and size that indicates good genetic quality.

The best-looking sperm are then injected into eggs.

The treatment builds on the success of intra-cytoplasmic sperm injection (ICSI), a therapy for male infertility that has enabled thousands to become fathers since it was developed in the early Nineties.

ICSI involves fertilizing an egg in a laboratory by injecting it with a single sperm.

As the sperm does not have to swim up to the egg and penetrate it, the method can help men whose sperm would otherwise be too weak.

Even when men produce no sperm, doctors can sometimes recover them surgically from the testes.

The team of Italian researchers, led by Monica Antinori, of the Raprui clinic in Rome, conducted the largest randomized controlled trial to compare outcomes for IMSI and ICSI.

The study involved 446 couples in which the man was infertile and the woman was not known to have any problems.

The results showed that the IMSI method could deliver considerable improvements in pregnancy rate.