Surrogate mothers: 'Our friend has given us a son'
21 August 2014 Last updated at 00:09 BST
The case of Gammy, a baby with Down's syndrome born to a Thai surrogate and allegedly left behind by the intended Australian parents, has caused international controversy.
This year it is projected that around 200 babies will be registered in the UK as being born through surrogacy.
But it is still illegal to pay for a woman to have your baby in the UK and any agreement drawn up is not legally binding.
There are calls for more regulation to protect parents and surrogates.
In some countries commercial surrogacy is legal.
BBC News met new parents Nick and Michael Scott-Kline with 18-month-old Elliot and surrogate mother Sarah Jones.
You can hear Catrin Nye's full documentary about Surrogacy on The Report on Radio 4 on Thursday at 20:00 BST.
Video Production: Andy Brownstone. Producer: Catrin Nye