Parents have long been told that “breast is best”—and with nearly 80 percent of all newborns breast-fed at least once, that message seems to have taken root. But there’s a stark divide between low- and high-income nations in whether a new mom continues breast-feeding, according to a two-part study published in The Lancet on Thursday.

Researchers concluded that the deaths of as many as 823,000 children under five could be prevented across the globe if breast-feeding efforts were scaled up. Universal breast-feeding could also prevent roughly 20,000 breast cancer deaths annually.

Low-income countries far surpass high-income countries in initiating breast-feeding and continuing it for up to two years. While more than 90 percent of babies continue to be breast-fed at six months and at 12 months in low-income countries, those figures drop to around 40 percent and 20 percent, respectively, in high-income nations. The U.K. and Canada have among the lowest rates of babies breast-fed at 12 months, while Senegal and Malawi have among the highest.

As countries continue to grow and develop, researchers fear their nursing rates will drop as well.

“As income increases, the trend is away from breast-feeding toward substitute milk instead,” Nigel Rollins, a coauthor of the study, told The Guardian. “We’ve seen this trajectory with developed countries and don’t want it to play out a second time in low- and middle-income countries.”

The World Health Organization recommends that infants be exclusively breast-fed for the first six months of their lives, with additional foods introduced alongside breast milk for the first two years.

Breast-feeding is often championed in developing nations as a means to protect babies from formula that could be mixed with contaminated water, causing respiratory infections and diarrhea. But the study also found that breast milk benefits babies in wealthy nations, with a 36 percent drop in sudden infant deaths. Researchers also found that children who are breast-fed are 26 percent less likely to become overweight or obese later in life.

Along with preventing breast cancer deaths, breast-feeding helps moms return to their prepregnancy weight and can reduce the likelihood of developing type 2 diabetes. The study also points to research that shows children who are breast-fed have higher IQs. By calculating potential earnings losses, researchers found that current breast-feeding rates short the global economy by $302 billion annually.

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With all these benefits, breast-feeding may seem like the obvious choice. The Lancet study points to aggressive formula marketing campaigns and lack of lactation support as deterrents to breast-feeding and called work “a leading motive for not breast-feeding or early weaning.” Short maternity leave, not enough lactation rooms, and unpaid breaks make holding a job and breast-feeding a challenge.

Researchers recommend government awareness campaigns and workplace interventions to support breast-feeding.

“The success or failure of breast-feeding should not be seen solely as the responsibility of the woman,” Rollins told The Guardian. “Her ability to breast-feed is very much shaped by the support and the environment in which she lives. There is a broader responsibility of governments and society to support women through policies and programs in the community.”