February 15 2018
Surrogacy is where a woman becomes pregnant with the intention of handing over the child to someone else after giving birth. Generally, she carries the baby for a couple or parent who cannot conceive a child themselves - they are known as "intended parents".
There are two forms of surrogacy. In traditional surrogacy, the surrogate mother's egg is used, making her the genetic mother. In gestational surrogacy, the egg is provided by the intended mother or a donor. The egg is fertilised through in vitro fertilisation (IVF) and then placed inside the surrogate mother.
It varies from country to country.
In countries including the UK, Ireland, Denmark and Belgium, surrogacy is allowed where the surrogate mother is not paid, or only paid for reasonable expenses. Paying the mother a fee (known as commercial surrogacy) is prohibited.
Commercial surrogacy is legal in some US states, and countries including India, Russia and Ukraine.
People who want to be parents may go abroad if their home country does not allow surrogacy, or if they cannot find a surrogate.
However, even here, the laws may vary. For example, some Australian states have criminalised going to another country for commercial surrogacy, while others permit it.
Experts say that countries popular with parents for surrogacy arrangements are the US, India, Thailand, Ukraine and Russia.
Mexico, Nepal, Poland and Georgia are also among the countries described as possibilities for surrogacy arrangements.
Costs vary significantly from country to country, and also depend on the number of IVF cycles needed, and whether health insurance is required.
Families Through Surrogacy, an international non-profit surrogacy organisation, has estimated the approximate average costs in different countries:
There are few statistics on how many children are born through surrogacy arrangements, as many countries do not formally record this.
Nicola Scott, a lawyer with UK family law firm Natalie Gamble Associates, says that about 25% of her firm's clients go to the US, often because they feel it is safer.
"The US has a very long history of surrogacy. One reason is that the parents know there are established frameworks in many states, particularly California, so there is safety associated with going there," she says.
Why do women become surrogate mothers? Sarah Wisniewski, Surrogacy UK
We're aware of how, just taking a year out of our lives can drastically help someone else's life.
The majority of us have our own children, although a couple of the surrogate mothers in our network are childless.
We appreciate and are grateful for our own children too - the majority of us just see pregnancy as something we find very easy - something we can do while getting on with our everyday lives.
"People who choose other destinations tend to do so because a surrogacy there typically costs a lot less than in the US."
In many countries, "surrogacy isn't illegal, but there's no framework to support it," Ms Scott says.
For example, Thailand does not have clear regulations surrounding surrogacy. However, legislation has been drafted to regulate surrogacy, and authorities now say the surrogates must be a blood relative of the intended parents.
Similarly, India is considering legislation which could "massively restrict surrogacy", Ms Scott says, and will "shut the door to singles and gay couples".
There are no internationally recognised laws for surrogacy, so many parents and children can be left vulnerable - or even stateless.
It can take several months to bring a surrogate baby back to the parents' home country, as they may not be automatically recognised as the legal parents.
"In Thailand, surrogates are seen as the legal mother, so if the parents leave the baby with the mother, she is legally responsible. This is one of the difficulties seen in the Gammy case," Ms Scott says.
"In India, the intended parents are seen as the legal parents," whereas under UK law, the surrogate mother is recognised as the legal mother.
"This means a surrogate baby born in India, for UK parents, is born stateless, and has to apply for British citizenship."