The survey, titled the "Multiple Indicator Cluster Survey", covered 43,000 households across the country. Carried out by the NSO and the United Nations Children's Fund (Unicef), the survey is the largest and most in-depth assessment of the situation of women and children ever undertaken in Thailand.

The survey provides data to measure the Kingdom's progress toward the Millennium Development Goals, which governments around the world have agreed to meet by 2015, as well as progress towards other international commitments.

The survey's results confirm that Thailand's rapid economic development and social development policies have resulted in significant social benefits, including improvements in children's nutritional status, school attendance, access to safe water and sanitation, and essential health services.

The survey found that the percentage of underweight children in Thailand had fallen from 19 per cent in 1990 to 9 per cent in 2006; 98 per cent of children of primary school age were attending school; the number of one-year-old children fully immunised against the six preventable childhood diseases was 83 per cent; and the percentage of the population with access to safe water and sanitation was 94 per cent and 99 per cent, respectively.

"These are very impressive achievements that Thailand can be proud of," said Tomoo Hozumi, the Unicef Thailand Representative, at the launch of the survey's results. "At the same time, the results show there are some remaining challenges in reaching the international goals, and that the country can definitely make further progress given its capacity, resources and track record so far."

Hozumi said one challenge highlighted by the survey was the country's low rate of exclusive breast-feeding. In Thailand, the percentage of infants being exclusively breast-fed during the first six months was only 5.4 per cent, one of the lowest rates in the world.

The representative noted that exclusive breast-feeding is the best way to guarantee infants get all the nutrients they need during this critical early period of their development, and he urged that the marketing of breast milk substitutes to mothers in Thailand follow internationally agreed standards and guidelines.

Hozumi also pointed out that Thailand trailed many other countries in regard to iodised-salt consumption, the best and most economical way to ensure an adequate amount of this essential nutrient in the daily diet. Severe deficiencies of iodine can result in mental retardation, while even mild deficiencies can restrict children's mental capacity and negatively affect their school performance.

"This is an area where more effort is needed," Hozumi said. "It requires the introduction of legislation that would make it compulsory to add iodine to all edible salt for human and animal consumption in Thailand. Many countries have already done this."

The survey also showed that much more needs to be done to educate the public about HIV/Aids. Less than half of 15- to 49-year-old women have comprehensive knowledge about HIV/Aids, which was measured by knowing at least two ways to prevent HIV transmission and rejecting three common misconceptions about HIV transmission.