Which Countries Are Best At Preventing Low Birth Weight? Which Need To Do More?

Six years ago, I was traveling in India, working on a story about measles. I was visiting a public hospital in New Delhi, when I walked into the waiting room and saw the tiniest baby I had ever seen.

An elderly woman — perhaps a grandma — was cradling the newborn in her arms. The little baby was wrapped in a blanket, and a tiny knit cap covered her head, which wasn't much bigger than a small orange. The newborn could not have weighed more than four pounds.

I couldn't believe this infant was simply sleeping in the hospital waiting room. Why wasn't the newborn in the intensive care unit?

For the first time, the World Health Organization has estimated the progress made in preventing low-weight births — a condition that raises the risk of health problems for a child's entire life. And the progress is slow — too slow, says epidemiologist Joy Lawn at the London School of Tropical Medicine.

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Each year, more than 20 million babies are born weighing less than 5.5 pounds, the WHO and UNICEF report Wednesday in The Lancet Global Health journal. Half of these babies are born in South Asia and a quarter in sub-Saharan Africa.

Since 2000, the world has reduced the rate of low-weight births by only about 3%, from 18% to 15%, the study found. Almost all that progress comes from low- and middle-income countries, where more than 90% of these births occur.

"Shockingly, progress is really slow in high-income countries," says Lawn, who helped to lead the study. For example, there has been almost no improvement in the U.S., U.K., Germany, Australia and New Zealand in the past 15 years.

For the study, Lawn and colleagues collected data on 281 million births from 148 countries. For countries lacking comprehensive health records, the team used household surveys to estimate the rate of low-weight births in 2015.

Sweden leads the world with the smallest rate, at 2.4%. Bangladesh has the worst rate, at 28%.

The U.S. ranked 31st, with an 8% rate — 20 slots below China. That rate means more than 300,000 babies are born in the U.S. each year weighing less than 5.5 pounds.

The study mentions two major reasons for the relatively high rate in the U.S.: the prevalence of fertility treatments and high rates of unnecessary C-sections.

In southern Asian countries, the major issue is poor maternal nutrition, which can restrict fetal growth. In Africa, the major drivers are high rates of teenage pregnancies and infections during pregnancy.

Regardless of the underlying reasons, being born underweight can have health repercussions for decades.

"Low birth weight is probably the single piece of information about you that most predicts your health throughout your whole life course," Lawn says. It increases the risk of stunting, disabilities and developmental delays during childhood and chronic conditions — such as heart disease — later in life.

"All of these outcomes result in human suffering, but they also perpetuate intergenerational poverty," Lawn adds. In other words, if the world can decrease the rate of low birth weight babies, it will simultaneously help reduce the rate of poverty.

But the problem has been a tough one to fix. Back in 2012, the World Health Assembly set the goal of reducing low-weight births worldwide by 30% before 2025. To reach that figure, Lawn says, the world would have to speed up its progress by more than double.

"This is a wake-up call to governments, to the U.N. and to all partners," Lawn says. "We must do more to tackle low birth weight. We owe it to every newborn around the world and to their families."