It's known by different names throughout the world - chai-yok in Korea, ratus in Indonesia, ganggang in Malaysia, bajos among Mayan healers and Venus smoke in North America. A centuries-old practice more common on the Asian subcontinent, steaming of the female genitalia over a pot of herb-infused boiling water is known for its curative effects on health and fertility. It is said to reduce stress, fight infection, clear haemorrhoids, regulate menstrual cycles and aid infertility, among other health benefits. And the practice is making something of a comeback. In Singapore, for example, Babies Bellies Javanese Massage & Spa offers a 20-minute treatment at S$50 (HK$310). The spa's managers claims it has seen a steady increase in the number of women who request the treatment, especially post-pregnancy. And it is catching on in the US where the upscale Juvenex Spa in New York has a 30-minute Gyno Spa Cure for US$75, while Tikkun Holistic Spa in Santa Monica, California, offers a 30-minute V-Steam treatment for US$50. There is folk wisdom - and even some logic - to support the idea that the carefully targeted steam may provide some physiological benefits for women. But there are no studies to document its effectiveness, and few Asian doctors we questioned had even heard of it. Dr William So, a specialist in Reproductive Medicine at Premier Medical Centre, says: 'There's no peer-reviewed information [on vaginal steaming] in medical journals. 'The first concern is the possibility of the moist heat causing burns to the sensitive region. And how much of the active ingredients are absorbed is questionable. There's no way for us to assess its efficacy.' Dr Jayanta De, professor and head of obstetrics and gynaecology at MVJ Medical College and Research Hospital in Bangalore, India concurs: 'Though lots of claims have been made regarding its gynaecological remedial capabilities, it requires evidence-based proof which is not yet available.' A typical session begins with chai-yok, or a pot of boiling water infused with 14 to 20 herbs. The primary herbal ingredients are mugwort and wormwood, which have alleged antibacterial, antiviral and antifungal properties. The moist heat opens the pores of the tissues it comes into contact with. The use of specific herbs adds layers of different healing benefits. The combination of herbs works to nourish, tone, heal, bring in fresh oxygenated blood, promote cleansing, and make supple the vaginal and uterine tissues. In South Korea, many women steam regularly after their monthly periods, as it's believed to boost circulation, supplying nutrition to the lower part of the body. Martha Tilaar Salon and Day Spa, which has branches across Indonesia, lists on its website the 120-minute Ken Dedes Princess Ritual as one of its signature indulgences. The package begins with a massage that claims to 'increase blood circulation, soothe nerves and muscles'. It's followed with a hot, herbal bath and a 'unique feminine smoking ceremony that aims to cleanse a woman's sexual organ and remove unpleasant odour'. 'You sit on a stool without a seat, just the frame. The therapist prepares a concoction of herbs that are smoked with small pieces of incense-like objects. This is placed under your stool and the fragrant smoke rises up between your legs into your nether regions,' says Ana Ow, a mother of two who tried the treatment at the Martha Tilaar Spa in Bintan. 'It felt like a sauna or steam room just for that area. I felt refreshed and clean after it.' Ow says she would recommend the treatment because she believes in Asian homeopathic remedies. 'Rituals such as these have been passed down from generation to generation for healing and rejuvenating purposes, way before Western medicine came up with clinical treatments and drugs that may act on symptoms but not heal from within.' Bang Wei-tin, a writer, has also tried the treatment. 'It lasts about 15 minutes and can be almost unbearable. Steaming is said to beautify and tighten the vagina wall and make sex better. A gynaecologist said it could open up the uterus, but I didn't feel any side effects.' The staff at Babies Bellies admit that the ganggang treatment hasn't been scientifically proven, but they believe the fact that it has been passed down through generations is validation of its efficacy in drying up stitches post-delivery, reducing excessive discharge and helping to tighten the vaginal wall. But they warn that the steaming shouldn't exceed 20 minutes. Obstetrician-gynaecologist Margaret Polaneczky of The Blog That Ate Manhattan, says: 'I'd avoid the vaginal steam spa. Especially if you are prone to yeast infections, since yeast loves a warm, moist environment.' Women who experience heavy menstrual cycles should avoid vaginal steaming during their periods. If you have a vaginal infection, open wounds, sores, or blisters, do not know if you are pregnant or think you may be, the treatment is definitely to be avoided. And if you have genital piercings, you might want to take them out. The heat could cause the piercing to scald you.