Scientists in America created human embryos using genetic material taken from three people in a highly controversial new technique.
The news comes amid a public consultation into the creation of three-parent babies in the UK.
Researchers in Oregon used genetic material from two women and a man to produce 13 normal human embryos.
Supporters say the technique could prevent some genetic diseases being passed from mother to child.
But the process is controversial because it involves deliberately altering the genetic material of subsequent generations.
Laurie Zoloth, a bioethicist at Northwestern University, has said that safety problems might not show up for several generations.
According to the report, which was published online by the journal Nature on Wednesday, researchers transplanted nucleus DNA into 64 unfertilised eggs from healthy donors. The eggs were then fertilised.
Roughly 20 per cent of the eggs showed normal development and went on to form early stage embryos. But 50 per cent of the eggs underwent abnormal fertilisation.
Shoukhrat Mitalipov, who led the research, said: “You can expect the first healthy child to be born [using this method] within three years.”
The report also revealed that four monkeys that were born in 2009 from eggs that underwent nuclear DNA transplants were still healthy.
The three-parent embryos were created by researchers at Oregon Health & Sciences University.
The UK’s Human Fertilisation and Embryology Authority is currently holding a consultation into the ethical implications of creating babies with three genetic parents.