Mums with babies aged under six months could see the advertising of infant milk formula for their children banned.
The Commerce Commission has backed a proposal to do so, saying the health benefits of breastfeeding could be affected by the unrestricted marketing and advertising of infant formula.
In November, the Infant Nutrition Council (INC), which represents the manufacturers, marketers and importers, applied to the commission to have its voluntary Code of Practice made mandatory for those in the industry.
The code restricts its members from marketing and advertising formula for babies under six months old, stops them from giving free samples to pregnant women and mothers in that age group and distributing samples to healthcare professionals as a sales inducement.
According to Women's Health Action, about 30 of the 70 companies manufacturing and marketing infant formula in New Zealand adhere to the code.
The commission has released a preliminary decision authorising the proposal. It is not known what penalties companies would face if they did not comply with rules if the proposal goes ahead.
The commission has called for submissions on the proposal and will make a final ruling after they close on March 25.
Chairman Dr Mark Berry said restrictions on marketing and advertising activities typically limited the amount of information available to consumers, reducing competitive pressure and making consumers worse off.
"In this instance, however, authorising the INC's Code of Practice is likely to have significant public health benefits.
"In particular, it is widely agreed that there are a variety of health benefits from breastfeeding, which could be adversely affected by the unrestricted marketing and advertising of infant formula."
INC chief executive Jan Carey said the commission's approval would ensure members, who cover the Karicare, Nurture and S-26 brands in New Zealand, complied with the code.
Ms Carey said the council supported breastfeeding as optimal for babies and infant formula as the next best substitute.
The Women's Health Action's maternal and child health promoter Isis McKay said unrestricted marketing had been shown to negatively impact women's efforts to breastfeed.
Christchurch mother-of-two Dawn Blyth, 32, has fed her four-week-old son Xavier infant formula since he was born. Her six-year-old old son Hunter was also fed with infant formula.
"Both of my boys are happy and healthy," she said.
"Our four-week old son has made excellent progress, meeting his milestones and putting on weight as he should be. Our six-year-old son has never had any problems."
Formula debate
• Commerce Commission draft decision:
• Infant formula for babies under six months not to be marketed or advertised.
• Follows a voluntary code already in place in New Zealand.
• Commission says public health benefits outweigh risk of anti-competitive behaviour.