London A British man is believed to have given birth, causing an ethical controversy.
The "male mother" started life as a woman but underwent a sex change. He is thought to have had the baby last year, while living as a man.
Medical experts said that if the womb is not removed in sex change surgery, there is nothing to stop a woman who becomes a man from having a child.
But others said that the welfare of the baby is paramount and queried how the child will deal with even the simplest of issues, such as whether to call the man "Mummy" or "Daddy".
Only a handful of "male mothers" have given birth worldwide and this is believed to be the first case in Britain.
Details were revealed by Joanna Darrell of the Beaumont Society, which provides support to those who have changed sex or would like to do so, a process also known as gender reassignment.
She said the man, in his thirties, inquired about the practicalities of having a baby after the surgery.
He was referred to another charity but later got back in touch to thank the society for its help and say he had had a baby.
This call came around six months ago. It has not been disclosed whether the child is a boy or a girl.
The charity that took the referral, the Gender Identity Research and Education Society (Gires), was unable to confirm the birth.
In 2008 Thomas Beatie, from Oregon, made headlines when he became the world's first "pregnant man" after a hysterectomy left his wife unable to conceive. He has now borne three children.