In spite of a high demand for surrogacy around the world, there are no international treaties or conventions - either for commercial or altruistic surrogacy.

“It booms in a legal vacuum,” says Professor Amritha Pande, of the University of Cape Town, an expert on international surrogacy.

“And, as one after another country bans commercial surrogacy, it moves from one to another. It just shifts a morally sticky issue elsewhere as the industry seeks ways to offer services at the lowest possible costs.”

Pande has spent more than a decade probing the once-booming industry in India.

In her book “Wombs in Labour”, she tells of how once grubby facilities became high-tech where women lived for nine months until they give birth and handed over the babies of those who had paid them.

Most, she said, in a recent presentation to a family law conference in South Africa, were mothers who had agreed because of financial desperation, to bear children for couples struggling to have their own, many of them foreigners and many of them gay men.

As one delegate at the conference said, these women are poor and illiterate “and I have yet to come across one who could sign her name”.

The commissioning parents come from all over the world, from countries where surrogacy is outlawed or just too expensive.

Then, in 2013 India banned gay surrogacy. Three years later it was to ban all surrogacy for international clients.

The industry then moved to Thailand , where it was banned, to Nepal, where it was banned, and then to Cambodia.

Now, African countries such as Nigeria, Kenya and Ghana are in the spotlight.

Professor Julia Sloth-Nielsen, children’s rights expert and law professor at the University of the Western Cape, says surrogacy has now taken root in Africa.

“This is partly because of the bans (in other countries), the declining number of children available for inter-country adoptions and the increasing availability of artificial reproductive techniques, even in places where you might not expect it.”

In her presentation to the conference, she raised the case of Chinese “tourist” Neo Kian Fu who has been charged, along with a doctor and a surrogate (who was the biological mother), with “attempting to traffic a baby” from Kenya to Singapore.

Sloth-Nielsen said while Kenya allows surrogacy, it’s only legal if there is proved infertility, if there is a genetic link and only for Kenyan nationals.

Nigeria, she says, is a different matter.

“There is no legal framework. There are reports of ‘baby factories’. There is a bill pending which, if passed, will allow for monetary compensation and cross border surrogacy but the commissioning parents must employ an inter-country guardian to look after the surrogate during and after pregnancy.”

Ghana, she says, has a “thriving commercial surrogacy industry”, again with no legislation.

“There have been public outcries about alleged exploitation.”

So what of the women who, in the words of Pande, are being used as “ovens to bake bread”.

And, what of the children born through these arrangements who can be born “stateless” because many northern countries refuse to acknowledge them.

In one case in Kenya, the British parents of twins (born through surrogacy) and named as the parents on their birth certificate, could not register them in Britain which regarded the surrogate as the “mother”.

The only option, they were informed, was to adopt them.

Pande says instead of bans, she advocates for “transparent and carefully thought-out laws” which regulate the industry and protects the rights of the surrogates including an “affirmation of their dignity” and to stop exploitation.

“Otherwise people just find ways to bypass the loopholes.”