A World Bank study finds health programs designed to reach the poorest people in developing countries often end up helping those who are better off instead.
Abdo Yazbeck, a health economist who helped write the World Bank study, says he was surprised at the extent to which the poor were not getting health services intended for them.
"The problem is health services do not reach poor people in numbers that we would like to see them."
An unintended consequence is that richer people get the services -- primarily, the World Bank reports, because of all the obstacles poorer people face.
Mr. Yazbeck says sometimes it is because people have to forego earning wages to get to a clinic, or they might have to pay for the services, or the distance they might have to travel is too great, or cultural norms might interfere.
"Women may not be allowed to go outside the home or go see a physician or a provider who is not a woman."
In India, he says, people in a lower social caste may not be allowed to seek care from someone in a higher caste.
"So what we tried to do with this project is try to learn which programs do seem to work better in reaching the poor and learning from them so we can try to improve our ability to reach poor people in other programs."
Mr. Yazbeck says when programs work, it is because countries receiving the aid make it a priority to ensure their success.
Some countries pay poor families to receive medical care or to send their children to school. Others provide health insurance to their poorest citizens.
The World Bank now wants to see if the programs that work can be adapted elsewhere so more of the world's poor can receive the help intended for them.