THERE are several reasons why families contact Tammy Charles.
An abnormal uterus.
Having a partner of the same sex.
But her clients share common ground: they can't have children the natural way.
Ms Charles, a former emergency nurse, founded a commercial surrogacy agency in Thailand nearly a year ago.
The Ulverstone-raised 45-year-old is the director of the Bangkok-based All Surrogacy IVF, a service that guides Australians through commercial surrogacy: a process where a woman is paid to carry and birth a child for another couple.
Commercial surrogacy is illegal in Australia and altruistic surrogacy is strictly controlled - meaning hundreds of couples are turning to the booming fertility industry in Thailand and India for the chance to have children.
Ms Charles and her husband Simon Davis were one such couple.
Their twin boys, Cooper and Jackson, were born via a Thai surrogate in 2012.
Since starting All Surrogacy IVF in May 2013, Ms Charles said she had arranged surrogates for 53 Australian families, with a 93 per cent pregnancy success rate.
While she described her job as ``the best in the world'', Ms Charles acknowledged the dark side of the fertility industry, which is largely unregulated in Thailand.
``To be honest, there are a lot of dodgy agencies popping up over there,'' she said.
``A lot of them just exist to make money from emotionally-motivated people.''
An internet search will turn up hundreds of surrogacy agencies in Thailand; the number of businesses has grown steadily since India tightened its surrogacy laws last year.
Commercial surrogacy is neither legal nor illegal in Thailand, and while there is little in the way of control, monitoring or regulation, it is tolerated by Thai authorities.
However, Mrs Charles said if people relied on thorough research and communication, there was no reason to see commercial surrogacy as a dangerous practice.
``Some people like to think [surrogacy agencies] just drag women off the street, pay them nothing and force them to become pregnant,'' she said.
``If you go through agencies who are reputable, who know what they are doing, it is a legitimate and professional industry.
``Because surrogacy is financially risky, and the people involved are so emotionally driven, what we do involves months and months of planning, checking, organising to ensure everyone is OK with what is happening.''
Ms Charles spent her youth travelling between Tasmania and Melbourne and ran her own hairdressing salon for 10 years before retraining as a nurse.
In 2006, at the age of 38, she met the man she would marry - Mr Davis.
Ms Charles said both were clucky for kids and, although she had four children from a previous relationship, medical reasons had forced her to undergo a hysterectomy at 32 making it impossible.
She said altruistic surrogacy in Victoria was not a viable option, given they did not know of anyone who would volunteer to bear their child without financial assistance.
In 2010, at 42 years old, Ms Charles began looking at Thailand as an option.
She said she used her medical background to research reputable clinics, and, after $35,000 and 35 weeks, she and Mr Davis welcomed their twin boys into the world.
After the birth, the couple shared their story on Channel 7's Sunday Night program, which led to hundreds of inquiries from couples across the country.
``We were inundated with requests for advice,'' Ms Charles said.
``All these people, who, for whatever reason, did not fit the right criteria for altruistic surrogacy in Australia, but still desperately wanted children.''
As All Surrogacy IVF's company director and clinical advisor, she acts as a link between the paying family, the surrogate mother, the doctor, the hospital and the Australian embassy in Bangkok.
She said her agency was one of the few that offered clients a ``total surrogacy package'' with flights, accommodation, legal documents and medical fees all included in the total cost, which she said typically ranged from $40,000 to $60,000.
``That is where a lot of the less reputable agencies get people,'' she said.
``They cite the cost, and then when the couple comes to pick up the baby, they throw all these extra fees and bills on top.''
Mrs Charles said her Thai surrogates were paid between $23,000 and $25,000 to carry and birth a child and were subject to an extensive medical checklist.
``Critically, they must have already had children of their own, so they know what it means to people to have a family,'' she said.
``One of the biggest fears clients have is that a surrogate is going to run off with the baby.
``I have never seen that happen, but we take a number of measures to ensure the emotional well-being of the surrogate and the client.''
Ms Charles said she would welcome the introduction of surrogacy legislation from the Thai parliament.
In 2010 the Thai Cabinet approved the draft Assisted Reproductive Technologies Bill, though further changes are expected based on the recommendations of the Medical Council of Thailand.
Once in place, the new laws would allow surrogacy in Thailand under more tightly controlled conditions, which Ms Charles said would help dismantle the dodgy dealers.
``It would mean better monitoring and it would mean the agencies that do the wrong thing by people would have a very hard time doing business,'' she said.
``The clinics who are doing the right thing would have nothing to worry about.''