Men becoming pregnant is imminent, a leading fertility expert is predicting, as medical research has paved the way through successful womb transplants on women born without them. 

There have been headlines of men being pregnant before, but until now they have been trans men who were born biologically female and chose to retain their female genitalia and reproductive organs. 

That could all change 'tomorrow,' predicts Dr Richard Paulson, who thinks womb transplants are making it possible for trans women biologically born male to have the procedure and give birth to their own children. 

Dr Paulson, president of the American Society for Reproductive Medicine, expects there to be demand from trans women and believes there is no longer any scientific reason why biological males cannot carry a baby. 

He told the Society's annual meeting in San Antonio, Texas, that there would be some challenges but it is possible. 

'You are talking about trans women. Someone who started out as a man, who became a woman,' he said. 

'There would be additional challenges, but I don't see any obvious problem that would preclude it. I think it would be possible.'

Asked how soon we could see the first biological males carrying their own babies, he answered: 'They could do it tomorrow.'

He clarified, though, that it was not as simple as someone walking into a surgery and asking for it.  

'It's still a very complicated procedure. It's a huge team, it's not something somebody can do in a community hospital and just get it done.'

Even if the procedure were successfully carried out on a man, there would still be further complications in the actual birth and it would not be exactly the same as a natural birth by a woman. 

This is because, he explained, the male pelvis is not wide enough for a baby to pass through and so the man would only be able to carry the baby but would then have to give birth by caesarean section each time. 

They may also require an additional hormone supplement to mirror the pregnancy of a woman.