Breast-milk substitutes in disaster-hit areas where clean drinking water is scarce have led to cases of diarrhoea, the second leading cause of death for children under 5 and a key cause of malnutrition among young children, experts say.
"Most people don't realise how dangerous that is. In pretty much every emergency in this region, we see infant formula donated," UNICEF regional nutrition specialist Dorothy Foote told the Thomson Reuters Foundation.
"Instead of infant formula, communities and mothers need to understand how important it is to keep breastfeeding."
Infant formula is aggressively marketed in Southeast Asia.
However, in disaster-hit areas, water supplies and infrastructure are often damaged or inaccessible, making safe drinking water - needed to mix formula and clean bottles - a rare commodity and increasing the risk of disease.
Giving out breast-milk substitutes and baby bottles during emergencies should be avoided, said a recent report by UNICEF, the World Health Organization (WHO) and the 10-member Association of Southeast Asian Nations (ASEAN).
"Many do not know that this is an inappropriate donation that amplifies risks of malnutrition, disease and death for young children," the report said.
Some governments have breastfeeding policies, but often they are not implemented - or enforced in cases of violations - said Yvonette Serrano Duque, a specialist in public health in emergencies for the independent Asian Disaster Preparedness Center in Bangkok.
Since 1986, the Philippines has had a "milk code" - executive order 51 - which regulates the marketing and distribution of breast-milk substitutes, and promotes the "benefits and superiority of breastfeeding".
While disasters are not specifically mentioned in the executive order, a government website on the issue says: "Breastfeeding is best for babies especially during disasters."
Nonetheless, faith-based groups in the aftermath of Super Typhoon Haiyan in 2013 solicited for infant formula donations, Duque said.
PROMOTING BREASTFEEDING
In Indonesia, the Ministry of Health and Indonesian Red Cross have promoted breastfeeding during disasters and providing breastfeeding rooms in temporary shelters, said Arfan Fathurohman, head of health and social services of the Indonesian Red Cross.
After the country's 2006 earthquake in Yogyakarta, UNICEF experts said distribution of breast-milk substitutes had been "uncontrolled and widespread", and they found more cases of diarrhoea among children who had received donated infant formula than those who had not.
The intergovernmental ASEAN Coordinating Centre for Humanitarian Assistance on disaster management (AHA Centre) plays a key role when well-meaning countries donate infant formula, which is turned down by disaster-affected countries with strong breastfeeding policies.
"AHA Centre tells the donating country that the affected country doesn't need this. What is good about this is that the member states do not lose face," said Arnel Capili, AHA Centre's chief of operations.
In normal situations, exclusively breastfed infants are 11 times less likely to die from diarrhoea and 15 times less likely to die from pneumonia - the two leading killers of children under five, researchers say.
Many women do not realise that if they switch to formula and breastfeed less, their bodies will decrease milk production, said Foote of UNICEF.
"If she stops (breastfeeding) to give her baby donated formula, then she may not have milk when the donations stop, or not enough money to continue formula," she said.
"There are lots of reasons why it's good to support mothers to keep breastfeeding, and make that common knowledge before an emergency happens, to prevent malnutrition in the first place."