Over 20 million babies around the world, equivalent to one out of seven, were born underweight in 2015, revealed a new global study published in the journal The Lancet Global Health.
Researchers from the London School of Hygiene & Tropical Medicine, UNICEF and the World Health Organization examined data from government databases and surveys in 148 countries between the years 2000 and 2015.
Researchers found that 91% of low-weight babies were born in low- and middle-income countries, with three-quarters of the total low-weight births taking place in sub-Saharan Africa and southern Asia.
On the other hand, only 7% of the low-weight births were noted in countries with a high income.
"Weight is the single most important factor about you at your birth that predicts your future health," said Professor Joy Lawn, director of the London School of Hygiene & Tropical Medicine's Maternal, Adolescent, Reproductive & Child Health Center and senior author of the new report.
“Low weight at birth can occur when a baby is born prematurely or is born at full term but is small for his or her gestational age due to growth restriction in the womb”, study co-author Dr. Mercedes de Onis of the World Health Organization said in a statement.
The authors said that babies with low birth weight have a bigger risk of undersized growth, developmental delays and adult-onset conditions.
"This is why reducing low birth weight requires understanding of the underlying causes in a given country," de Onis said.