Doctors in France announced the country's first birth of a "saviour sibling" to be a close genetic match to save a brother or sister suffering from a fatal genetic disorder.
The baby was born at the Antoine Beclere Hospital in Clamart, in the suburbs of Paris, said doctors Rene Frydman and Arnold Munnich.
The child, born to parents of Turkish origin and named Umut-Talha (Turkish for "our hope"), was conceived through in-vitro fertilisation and was born on January 26 with a weight of 3.65 kilos (8.03 pounds), they said.
"He is in good health," Frydman told AFP.
The child's embryo was genetically selected to ensure he did not carry the gene for beta thalassemia, from which his siblings suffer, but was also a close enough match to provide treatment cells from umbilical cord blood, a rich source of stem cells.
Beta thalassemia produces an abnormal form of haemoglobin, the protein in red blood cells which carries oxygen around the body. It causes destruction of red blood cells, which in turn leads to anaemia.
The world's first "saviour sibling" was Adam Nash, born in the United States in 2000.
The issue has been hedged with moral concerns about so-called designer babies and the morality of conceiving life to help a child with a genetic disorder.