A baby was born with DNA from three separate people after a special IVF procedure in the United Kingdom., in a first-of-its-kind case in the country, the fertility regulator said.

According to reports, the Human Fertilisation and Embryology Authority (HFEA) confirmed "less than five" babies have been born in the U.K. after mitochondrial donation treatment (MDT) as of April 20 this year.

HFEA did not give further details to avoid families being identified, the Guardian reported after receiving the information from a freedom of information request.

The aim of the treatment is to avoid women passing on defective genes in the mitochondria – tiny rod-like power plants in cells that supply energy – and prevent children from inheriting conditions.

The technique involves giving a woman an IVF baby with DNA from three individuals.

The baby will have nuclear DNA from its mother and father which define key characteristics such as personality and eye colour.

In addition, it will have a tiny amount of mitochondrial DNA provided by a female donor – the third "parent."

Britain became the first country in the world to formally allow mitochondrial replacement therapy (MRT) when the HFEA gave a cautious green light to the procedure in 2017.

In 2018, fertility doctors at the Newcastle Fertility Centre at Life were given permission by HFEA to give two women MRT.

In 2015, MPs and peers paved the way for the change by voting to alter the Human Fertilisation and Embryology Act which sets the legal framework for fertility research and treatment.