It was certainly one of the most arresting pictures of the week, echoing in a most unexpected way that famous shot of a naked Demi Moore at the height of her pregnancy. It was all there: the growing bulge, the protective hand on the bump, perhaps feeling for the baby's heartbeat, and then finally the expectant parent's beard.

The beard needs some explaining. The fact is that this is not a regular pregnant parent: it is an American man, beard and all, called Thomas Beatie. He is 34, lives in Oregon and is married to a woman called Nancy.

The reason Thomas can be pregnant at all and is expecting a girl in July is because he used to be a woman. He was born in Hawaii and was originally called Tracy Lagondino.

When she grew up, Tracy had a sex change that involved receiving testosterone injections; she also had her breasts removed but retained the female reproductive organs.

Thomas wrote about his extraordinary story in the American gay magazine The Advocate.

"How does it feel to be a pregnant man? Incredible," he said. "Despite the fact that my belly is growing with a new life inside me, I am stable and confident being the man that I am. To Nancy, I am her husband carrying our child - I am so lucky to have such a loving supportive wife. I will be my daughter's father, and Nancy will be her mother."

He said wanting to have a biological child was neither a male nor female desire but a human desire.

"Sterilisation is not a requirement for sex reassignment, so I decided to have chest reconstruction and testosterone therapy but kept my reproductive rights."

In preparation for the pregnancy, Thomas stopped taking the testosterone and arranged for anonymous sperm donation (his wife had a hysterectomy some years ago).

It had been about eight years since Thomas's last menstrual cycle so it was, he said, not a decision that the couple took lightly. "My body regulated itself after about four months and I didn't have to take any exogenous oestrogen, progesterone or fertility drugs to aid my pregnancy."

The couple have said they have faced discrimination from doctors reluctant to help them do what they wanted. "Doctors have discriminated against us, turning us away due to their religious beliefs," said Thomas.

"Healthcare professionals have refused to call me by a male pronoun or recognise Nancy as my wife.

"Receptionists have laughed at us. Friends and family have been unsupportive; most of Nancy's family don't even know I'm transgender."

Thomas also said he faced some negativity from his own family, including after Thomas's first ectopic pregnancy. "When my brother found out about my loss, he said, It's a good thing that happened. Who knows what kind of monster it would have been'."

Thomas is though not the first transgender man to have a baby. Lisa Masterson, an obstetrician in Los Angeles, told ABC TV: "A transgender man can be pregnant because he has the same organs as a woman. But it's really important that he doesn't take any testosterone early on in the pregnancy and later on. That can cause male-type characteristics in the female baby."

And Thomas believes being a transgender man could actually make him a better parent.

"A man whose desire for a child is strong enough to overcome the obstacles that transgender men must face in bearing one is likely to be an extremely caring father."

There has been some doubt about Thomas's story, though. One of his neighbours told ABC: "I couldn't say that he looks pregnant. I can stick my stomach out and almost make it look like that. I think it's kind of bizarre. I don't know if I believe it or not."

Sometime in July, we will know the truth.