Britain will become the first nation to legalise a "three-parent" IVF technique which doctors say can prevent some inherited incurable diseases, but which critics fear will effectively lead to "designer babies".
After more than three hours of debate, lawmakers in the British parliament's upper house voted on 24 February for a change in the law to allow the treatments, echoing a positive vote in the lower house earlier this month.
The treatment, called mitochondrial transfer, is known as "three-parent" IVF because the babies, born from genetically modified embryos, would have DNA from a mother, a father and from a female donor.
During the debate Lord Deben tabled a delaying motion, asking whether the amendment was in compliance with both UK and European law.
Labour Lord Robert Winston, himself a Professor of Science and Society at Imperial College in London, argued delaying the treatment would lead to termination of pregnancies in some cases.
"Because of course if we do delay this measure we are committing a number of people, as he will understand I'm sure very well, to termination of pregnancy and we will also be terminating not only their pregnancies but also of course having a number of lost pregnancies, loss of life for those women. Is that what the noble lord really wants in passing this motion?" said Lord Winston.
Lord Deben argued that his motion would not cause any further delays.
"The fact of the matter is that the time that is going to be taken for the human embryology committee and the terms under which it can give the permissions is more than the time that it would take to have this committee that I put forward. It will not hold it up for one moment."
When Lord Deben's motion went to a vote the lawmakers voted 280 to 48 against it, thus allowing the treatments to take place.
Although the techniques are still at the research stage in laboratories in Britain and the United States, experts say that now legal hurdles have been overcome, Britain's first 3-parent baby could be born as early as 2016.
Mitochondrial transfer involves intervening in the fertilisation process to remove faulty mitochondrial DNA, which can cause inherited conditions such as heart problems, liver failure, brain disorders, blindness and muscular dystrophy.
Mitochondria act as tiny energy-generating batteries inside cells, and around 1 in 6,000 babies around the world are born with serious mitochondrial disorders.