For years foreigners have come to Thailand for medical care, enticed by cheap prices and great beaches, and now some clinics are carving out a niche with fertility treatments too expensive or too controversial elsewhere.
Among the latest treatments offered is a procedure creating fierce ethical debate and available in just a handful of countries -- a treatment that allows couples to decide whether to give birth to a boy or a girl.
The service, known as preimplantation genetic diagnosis (PGD), is available to women having in vitro fertilization (IVF), and screens embryos for gender before they are implanted in the womb.
"Many people come from Australia because the government does not allow sex selection," said Pinya Hunsajarupan, a doctor at Jetanin Institute for Assisted Reproduction, the biggest fertility clinic in Thailand.
"They also come from China and India," Pinya said.
IVF is the most common procedure for the so-called "fertility tourists." The process can cost more than US$10,000 in Europe or North America, but could be as little as one-third that amount here.
"Most [foreigners] come because treatment in Thailand is much cheaper," said Phattaraphum Phophong, a fertility specialist at Bumrungrad International hospital.
He estimates that foreigners account for about 60 percent of the 500 patients that visit the hospital's fertility unit each month, with clients coming from Europe, the US, Japan, the Middle East and other countries in Asia.
"Some come here for travel as well," Phattaraphum said. "They have the first treatment and they go to Phuket for a week."
But sun and sand are not the only draw.
The Jetanin Institute is one of a handful of Thai clinics offering PGD which tests the chromosomes of embryos created outside the body for genetic diseases such as cystic fibrosis.
The process can also test embryos for gender, raising fears that people would try to create "designer babies" with the sex of their choice.
The technique is banned in many countries, but Thailand's Medical Council has only advised against sex selection, meaning clinics can take advantage of a gap in the market.
Dennis House, an international consultant at the Bangkok-based Ramkhamhaeng hospital group, said he began thinking about offering the service after he read news stories about sex selection in the US.
Six weeks ago the group began offering a range of reproductive services aimed at foreigners, including surrogate mothers, sperm and egg donors and PGD.
"I've had probably 30 to 40 inquiries in that time," House said.
"Many are from the US ... and also some from Europe and Australia where I guess there are some regulatory problems," he said.
House says he would be reluctant to offer PDG for gender selection without discussing it in depth with the patient.
"If they come to us and say I have seven daughters and would like a son, it's not my decision at that point," he said. "Personally I am a Buddhist and don't believe in intervening like that."
Pinya said that he was not too concerned about the ethical issues because very few were having the treatment, which costs US$7,000 to fertilize an egg and then test for its gender.
But Phattaraphum is worried about the way the increasing number of new treatments are used.
"I think we have to respect the embryo as a human, I don't think we should be able to select boys or girls," he said.