Researchers from the University of California, San Diego report that high rates of infant mortality in South Asian nations are liked to mothers having babies in rapid succession at an early age.
Writing in the journal International Journal of Gynecology & Obstetrics, Dr. Anita Raj, a professor of medicine at UC San Diego, and her colleagues contend that women younger than 18 years old who have less than 24 months between babies are "fueling" high infant mortality rates in Bangladesh, Pakistan, India and Nepal, where one birth in 14 to a young mother ends in the death of the infant within a year.
In India and Pakistan, nearly a quarter of the infant mortality rate was linked to young women who had their children rapidly, representing about 200,000 deaths in 2012 in those two nations alone.
In Bangladesh, however, only the short inter-pregnancy interval was linked to infant mortality, while in Nepal the researchers found the inverse.
However, Raj said that the comparisons may be imperfect.
"The data in India and Pakistan were collected four to five years prior to the data in Bangladesh and Nepal," she said, "and therefore represent different cross-sections of time. In addition, both India and Pakistan have higher burdens of infant mortality - in absolute and relative terms - than Bangladesh or Nepal."
The data was collected by an analysis of national demographic and health surveys taken in the four nations.
However, the research still underscores concerns about women's rights, including the social consequences of child marriage and young motherhood. A previous study by Raj and her colleagues found that 10 million girls under age 19 are married each year worldwide, usually under the force of local traditions and customs. Nearly half of these compulsory marriages occur in South Asia.
Other studies have found that childhood brides are more likely to live in poverty, lack education or basic literacy, have heath problems and die young, the researchers said in a statement.
"There is inadequate recognition that issues like early marriage of girls are primary drivers of problems like infant mortality in the region," Raj said, adding that measurable improvements in this area, including greater access to education and health care, have been made in Nepal and Bangladesh. But other issues, such as contraception use, remain persistently problematic.
"Infant mortality is a significant public health issue in South Asia," the researchers wrote. "According to United Nations data, the infant mortality rate worldwide is 49.4 deaths per 1,000 live births. In Pakistan, it is 70.90; India, 52.91; Bangladesh, 48.98 and Nepal, 38.71. By comparison, the infant mortality rate in the United States is 6.81 and just 1.92 in Singapore, lowest in the world."