A new Japanese fertility technique called round spermatid injection has allowed 12 sterile men to have babies, according to the Daily Mail. The technique involves the injection of a very young sperm into a woman's egg and is ideal for men with sperm production problems that prevent proper egg growth.

Round spermatid injection was first used in the 1990s and led to a handful of babies around the world. However, concerns of genetic abnormalities grew due to the immature sperm, and the technique was subsequently banned. The new method uses a refined method of the same technique and led to the creation of 14 babies from just 12 men.

"Round spermatid injection was effectively used in our clinic and resulted in the birth of 14 healthy babies," said the team of researchers from the Institute for Assisted Reproductive Technology (ART) in Fukuoka, Japan.

So far, the children appear to be healthy and none of them have shown any signs of physical or mental problems, according to the Belfast Telegraph.

"Although the current success rate of round spermatid injection is not very high compared with intra-cytoplasmic sperm injection (Icsi), this procedure can be the last resort for men who cannot produce spermatozoa but wish to use their own genetic material to produce offspring," the team said.

Despite the success of the technique so far, it is currently not allowed in the UK, according to The Guardian