Almost all parents and pregnant women in China, Vietnam and the U.K. are exposed to "aggressive” formula milk marketing campaigns that breach global rules set up after scandals more than 40 years ago, according to a new report.

The marketing techniques can push women away from breastfeeding and include everything from giving away free samples to executives setting up or joining "mums' groups" on popular messaging apps, the report from the World Health Organization (WHO), UNICEF and M&C Saatchi said.

Health workers are also targeted, with gifts, funding for research and even commission from sales — all practices that are banned under international guidelines for the marketing of formula milk.