Last month it was reported that children in the UK had been born using mitochondrial donation, eight years after the technique was regulated.
The IVF procedure uses genetic material from a mother and father and a tiny amount from a third female donor, with the aim of preventing the inheritance of mitochondrial diseases. These diseases are incurable and can be fatal.
The news gives hope to women carrying mitochondrial disease, yet Dr Dagan Wells, Professor of Reproductive Genetics at University of Oxford, says scientists have many questions.
Mitochondrial donation has been performed in other countries where its use is not regulated. The first baby created using the technique was born in Mexico in 2016.