In 2016, Britain could welcome its first-ever baby born to three parents.
MPs are set to vote next week on regulations to make mitochondrial transfer legal, as scientists hope a new study will convince the country's fertility regulator the IVF technique is safe.
Pronuclear transfer sees the genetic material of three people combined into one embryo, and involves the creation and destruction of fertilised eggs.
Senior figures in the Church of England and Catholic Church have warned that no other countries have allowed the controversial procedure, while some scientists have called for further research.
Here's what you need to know about the procedure:
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