One reason is that, despite health professionals' advice, parents face a well-resourced baby milk industry that relentlessly promotes its product, implying that the best efforts of science are better for baby than nature's way.

Much of the advertising violates the International Code on Marketing of Breast-milk Substitutes drawn up by the WHO and the UN children's organisation Unicef in 1981. But the government has done little to make brands toe the line, in part because of its reluctance to restrict a market in a city that prides itself on economic freedom.

But moves towards adopting a code to regulate milk formula advertising are finally progressing, not least since the revelation last year that several Japanese brands, available in Hong Kong on the unofficial, or grey, market, lack some essential nutrients.

After hundreds of babies fed on the Japanese formula had to be checked for iodine deficiency, the public - and some manufacturers - is coming around to the view that legal measures are needed to ensure milk formula standards.

"While some people consider claims [by manufacturers] useful for consumers, others are sceptical about any possible exaggeration or even misleading statements or representations made for the mere purpose of boosting sales," the draft code reads.

But the question remains: will the code, the first in the world to combine rules on marketing practices, labelling and quality standards for baby milk, be enough to crack the resistance of Hong Kong women to breastfeeding?

A consultation period on the code, which will be voluntary at first but is expected to form the basis for two pieces of legislation, has been extended until the end of next month.

The first law will lay out the content and nutritional composition of infant formula. It is expected to face little resistance.

The real challenge for the government will be in legislating to curb false claims by formula manufacturers. Banning false claims, as governments around the world have discovered, is complicated by the fact that the government must first research the benefits or otherwise of substances manufacturers claim are good for a child's development.

The details of the draft code have triggered strong opposition from manufacturers. Six brands, including Mead Johnson, Abbott and Nestle, formed the Hong Kong Infant and Young Child Nutrition Association. It opposes aspects of the plan, which the group describes as "radical".

"There is no scientific evidence to show promotion of food for children aged six months or above has affected the breastfeeding rate," the association said. The group says it is acceptable for children over six months to have formula and breast milk, and that the new policy "should not demonise mothers who cannot breastfeed".

Although they agree that marketing tactics aimed at mothers of children under six months should be regulated, they see no need for the controls to extend to older children.

"A three-year-old boy can eat solid food along with milk. He can eat potato chips and drink coke. Why is the government only banning formula makers from advertising?" association secretary Pingo Luk Yip-Shing said. He said over-regulation would go against free-market principles and damage the rights of consumers to information.

But Dr Patricia Ip Lai-sheung, chairman of the Unicef Baby Friendly Hospital Initiative Hong Kong Association, said such adverts did little to help parents choose the best products.

"They usually implant the concept that their brands have the most magical formula to boost the babies' IQ and health," she said. "The adverts have brainwashed parents and made them believe that if their children do not drink the milk, they will be at a disadvantage in competing with other children."

Paediatricians and pharmacists have long pointed out there is not enough evidence to show that substances such as AA, DHA and ARA that are often mentioned in formula adverts have the effect the advertising claims.

Dr Robert Scherpbier, head of health for Unicef China, said breast milk contained all of the substances promoted in the advertising - in fact, the manufacturers were in a race to make their product as close to breast milk as possible.

"According to several studies, the average IQ of breastfed children is 3.16 degrees higher than other babies, and the difference is particularly notable among pre-term infants," he said.

Scherpbier added that formula brands conveniently forgot that choosing formula over breastfeeding brought risks.

According to the WHO, the chance of a child who is not breastfed dying in the first two months is 5.8 times that of breastfed children. In Brazil, those under six months also had a 14 times greater risk of dying from diarrhoea and four times the risk of dying from pneumonia.

One measure the government has implemented - a ban on the distribution of free formula samples in public hospitals - has already had a substantial effect, according to a University of Hong Konh study.

The number of mothers who breastfeed their babies in the 48 hours after giving birth in a public hospital has more than doubled, up from 17.1 per in 2006/07 to 41.5 per cent this year. Typically, they breastfeed for 11 weeks, up from eight previously.

But formula manufacturers are still offering samples - half of the 1,230 mothers interviewed said they had been approached outside hospitals.

One 40-year-old mother said she had been approached by salesmen on several occasions, most often outside Family Health Service clinics, a favourite spot for formula promotion.

"I have declined the free sample," she said. "But that is only because I am clearly aware that breastfeeding is the best and am determined to do it. I believe those mothers who are less determined may take them."

Ip said formula samples were a concern because once a mother began using it, the amount of breast milk she produced would fall.

"It is a very cunning tactic," she said. "Many mothers may be tempted to use the free sample when they feel frustrated or tired, or simply because they do not want the powder to be wasted. Once they finish a can, they may find they aren't producing milk and have to rely on the product."

At a recent media gathering, representatives of manufacturers said some marketing tactics used by the "bad seeds" in the industry should be banned.

"If our promotions are causing discomfort to the government, we are willing to discuss a better way of doing it," said Regina Tam Chuk-ching, marketing director of Mead Johnson. "We will be happy if the government issues a guideline on how we should promote our products, but the best way is not to ban all advertising."

But on other aspects of the draft ordinance, manufacturers are less willing to compromise. For example, the code specifies that health warnings must be at least 2cm deep. Another label, not less than 1.5cm deep, should instruct parents to use water heated to 70 degrees or above to mix the formula.

One manufacturer said some formulas contained probiotics - live micro-organisms that may help with digestion - that may be killed off by very hot water.

"There are some fundamental aspects we cannot agree with," Tam said. "It is not clear how much we can comply with it ... I believe some manufacturers can follow 80 per cent, some can comply with 90 per cent."

But Ip and Scherpbier insist that such rules are needed because hot water kills bacteria.

One thing doctors, breastfeeding advocates and formula manufacturers agree on is that even if the code becomes law, it will not be enough to encourage more mothers to breastfeed. Other factors include the high number of working mothers and relatively short maternity leave.

All parties say the government should do more to promote breastfeeding, including taking another look at hospital practices to make maternity wards a lactation-friendly environment, extending maternity leave, promoting education and research, and providing places for mothers to breastfeed or pump milk in private.