Updated Feb. 3, 11:34 | The House of Commons voted Tuesday to allow scientists to use the DNA of three people to create a baby by a vote of 382-128. Now the bill moves to the House of Lords before becoming law. If it passes, it would make Britain the first country in the world to allow embryos to be genetically modified.

Original story from Feb. 1, 7:16 p.m. |Should doctors be allowed to exchange bad genes for good ones in order to produce a healthy baby?

That’s what members of Parliament are set to decide on Tuesday in the United Kingdom when they vote whether to legalize a provocative technique of three-person in vitro fertilization that gives the offspring genes from a mother, a father and from a female donor.

If passed, the U.K. would be the first country in the world to legalize this kind of IVF.

On Sunday, international advocates urged Parliament members Sunday to consider families at risk of incurable genetic disorders when weighing the controversial fertility treatment, known as mitochondrial donation, next week.

The vote “offers families the first glimmer of hope that they might be able to have a baby that will live without pain and suffering,” representatives from advocacy groups like the U.S.-based United Mitochondrial Disease Foundation wrote in an open letter to British lawmakers, Reuters reported.

Critics, however, say mitochondrial donation could lead to the creation of “designer babies.”

During the procedure, a modified egg, made by replacing faulty DNA from the mother’s egg with healthy DNA from the female donor’s, is fertilized and a healthy embryo is implanted into the mother.

This technique removes the risk of the child later suffering from diseases and conditions like epilepsy or blindness caused by defective genes.

In June 2014, a panel of scientists came out in support of three-person IVF. London’s charity organization Nuffield Council on Bioethics deemed the technique ethical for families at risk of passing on life-threatening hereditary diseases in 2012.