Many of the world’s poorest countries lack basic services for young children, and finding the resources to send children to preschool is a struggle. But the benefits greatly outweigh the costs, according to a new study on early childhood developmental interventions. Low- and middle-income countries that managed to enroll 25 percent to 50 percent of their children in preschool would recoup $6.40 to $17.60 for every dollar invested, the researchers estimate.

The study is part of a two-paper series, published in October in the journal The Lancet. It looked at how inequalities that begin in the womb and continue through early childhood — such as malnutrition, disease, maternal depression and lack of access to early child development programs — can continue to affect children throughout their lives, and even into the next generation.

Poverty-related problems keep more than 200 million children around the world from meeting their developmental potential, the same researchers found in a 2007 Lancet series. In the new series, they examine the root causes of those disparities, and how early interventions can help.

“What happens over time is that there are basically two tracks. A lower track that is less optimal and a higher track that is more optimal,” says Maureen Black, PhD, a psychologist at University of Maryland School of Medicine and one of the study’s authors. “And over time, the gap [between the two] widens.” The child on the lower track is less likely to go to school, to benefit from school and eventually to earn good wages.

But, Black says, the research shows that early interventions can reduce the gap between the two tracks. The researchers reviewed the literature on 42 such programs from around the globe, such as preschool, parental education programs and nutrition education programs. The study’s authors are an interdisciplinary consortium of pediatricians, psychologists, economists and others called the Global Child Development Group.

The great challenge in reaching the 200 million children at risk, the researchers say, will be in figuring out how to expand interventions that have worked on a small scale, finding the funding to do so and coordinating among the many government agencies — education, social services and others — that could deliver them.

“The publication in the Lancet is not an endpiece, it’s a mechanism,” says Black. “It gives us more credibility to push for the endpiece, which is evidence-based, high-quality programs for kids that are taken up by governments.”