"This series strengthens the evidence that a nation's economic advancement is tied to the first 1,000 days of every child's life," says Black. "Malnutrition can haunt children for the rest of their lives. Undernourished children are more susceptible to infectious diseases and achieve less education and have lower cognitive abilities. As a result, undernutrition can significantly impede a country's economic growth." While some progress has been made in recent years, Black and colleagues estimates that over 165 million children were affected by stunting and 50 million by wasting in 2011.

Maternal nutrition is essential for the health of the mother and the survival and development of her child. The study estimates that 800,000 neonatal deaths are caused by fetal growth restriction. Furthermore, newborns who suffer from this and survive are at a substantially increased risk of stunting during the first 24 months after birth.

Undernourished women are more likely to die in pregnancy, to give birth prematurely, and to have babies who are born premature or too small for their gestational age. Over a quarter of all babies born in low- and middle-income countries are small for their gestational age -- putting them at a significantly increased risk of dying. And more than one quarter of all newborn deaths are attributed to restricted growth in the womb due to maternal undernutrition.

An article accompanying the Series, led by Professor Joanne Katz, Department of International Health at the Bloomberg School, provides in-depth evidence on the mortality risk of infants small for their gestational age. Past studies have focused on low birth weight, but this can exclude many children who exceed the standard weight limit but were born prematurely or are small for their gestational age. "To prevent neonatal deaths, we should track whether the baby was born too small or too soon, not just the baby's birth weight. This will allow us to better implement the appropriate interventions to prevent these conditions and improve survival," says Katz.

"Countries will not be able to break out of poverty or sustain economic advances when so much of their population is unable to achieve the nutritional security that is needed for a healthy and productive life," explains Black. "We need to redouble our efforts and invest in what we know works. As the study led by Professor Zulfiqar Bhutta of Aga Khan University shows, scaling up 10 proven interventions -- including treatment of acute malnutrition, promotion of infant and child feeding, and zinc supplementation -- can already save 900,000 children a year."