The first baby with three parents contributing to its DNA has been born in Mexico, according to New Scientist.
The baby boy was born to a Jordanian couple on April 6, and the procedure was done in the hopes of stopping him from inheriting a genetic condition from his mother.
It's a controversial technique where the nucleus of the mother's egg is removed and inserted into a donor egg, which has had its own nucleus removed.
The mother has Leigh syndrome, a fatal disorder affecting the nervous system of infants. Its genes are found only in the mitochondrial DNA, not the nucleus.
Currently the procedure has only been legally approved in the UK, so the US-based team performed the procedure in Mexico, where "there are no rules", says Dr John Zhang.
And it seems to have worked. Five embryos were created, only one of which developed and was implanted into the mother.
While she previously had several miscarriages and both of her children died young due to Leigh syndrome, the boy is healthy so far, New Scientist reports.
Less than 1 percent of his mitochondria is mutated, and it's thought problems arise after around 18 percent is affected.
Dr Zhang says the procedure was the right decision to make.
"To save lives is the ethical thing to do," he says.
The baby will continue to be monitored as he grows older to see if he does develop mitochondrial issues.
Professor Sian Harding reviewed the UK procedure's ethics, and told New Scientist this technique seems to be ethical.
"It's as good as or better than what we'll do in the UK," she says.
But the last time embryologists attempted a three-parent baby, it didn't end well. In the 1990s a donor's mitochondrial DNA was injected into another woman's egg, which was then fertilised with the father's sperm.
The technique was banned after some of the babies ended up developing genetic disorders.
However, with the removal of the donor nucleus in this procedure it's hoped the same complications won't occur, as there will only be one source of mitochondria rather than two.
The findings will be discussed by the team at the American Society for Reproductive Medicine's Scientific Congress in October.