A third of young children in low- and middle-income countries are failing to meet basic milestones

The researchers used data collected between 2005 and 2015 based on caregiver report using the Early Childhood Development Index (ECDI) for 99,222 3- and 4-y-old children living in 35 LMICs as part of the Multiple Indicator Cluster Survey (MICS) and Demographic and Health Surveys (DHS) programs. They estimated that 14.6% of children in these 35 countries had low ECDI scores in the cognitive domain, 26.2% had low socioemotional scores, and 36.8% performed poorly in either or both domains. Of the 35 LMICs studied, those with the highest percentage of low-scoring children included Chad (67.0%), Sierra Leone (54.3%), and Central African Republic (54.1%), while those with the lowest percentage included Bosnia (4.4%) and Montenegro (4.3%). When extrapolating models to all LMICs, the authors estimate that 80.8 million 3- and 4-y-old children -- or 32.9% of those living in these countries -- are failing to meet basic cognitive or socioemotional milestones. An additional 16.7% of children are estimated to do well with respect to their cognitive and socioemotional development, but experience stunted physical growth.

The measure used to define cognitive and socioemotional development in this study focused on a narrow range of early skills, including children's ability to follow simple directions, work independently, control aggression, avoid distraction, and get along well with other children. Future research is needed to examine a broader range of developmental skills and age groups, as well as to identify possible interventions for mitigating these developmental setbacks.

Developmental deficits are most common in the poorest countries of the world. As the authors write: "Low development scores were largely concentrated in areas of the world facing continued high exposure to risk factors such as infectious disease, malnutrition, poverty, and low availability of high-quality healthcare and educational resources."