Study finds that healthy children across four continents reach similar neurodevelopmental milestones

The INTERGROWTH-21st Project, an international consortium that includes researchers from the SickKids Centre for Global Child Health, led by the University of Oxford’s Nuffield Department of Women’s & Reproductive Health, has already shown that healthy, well-nourished women, free of disease, living in a clean environment and receiving good antenatal care have children with similar skeletal growth patterns inside the womb, at birth and up to the age of two. This research has produced a unique set of international standards for monitoring growth, which perfectly match the existing World Health Organization (WHO) Child Growth Standards that are being used in virtually every country in the world.

Now, the INTERGROWTH-21st researchers have found that attainment in early childhood of neurodevelopmental milestones (relating to cognition, language ability and motor skills) is, like physical growth, very similar among children across diverse geographical and cultural settings, provided that their health and nutritional status are adequate. The findings are unique because neurodevelopmental markers of early childhood have not been studied in this way before.

The researchers assessed 1,307 healthy two-year-old children of urban, well-nourished, educated mothers, who were enrolled in the study during early pregnancy in Brazil, India, Italy, Kenya and the UK. The children were assessed using a specially developed psychometric tool, standard visual tests and WHO motor milestones. In 14 of the 16 measures, the percentage of total variance that could be attributed to differences between populations ranged from 1.3 per cent (cognitive score) to 9.2 per cent (behaviour score). This means that, across a comprehensive set of indicators of physical and early child neurodevelopment, less than 10 per cent of the variability was based on the child’s genes (nature); the rest is environment (nurture).

“Our findings from a carefully selected cohort across varying geographic regions and ethnicities, strongly suggest that health, nutrition and development potentials for children are the same everywhere in the world, and that the maternal health and nutrition is an important driver for birth outcomes as well as developmental trajectories up to 24 months of age,” said Dr. Zulfiqar Bhutta, Co-Director, SickKids Centre for Global Child Health, who is an author of the study. “Future studies should evaluate these cohorts of children at school age and beyond.”

Professor José Villar of the University’s Nuffield Department of Women’s & Reproductive Health, who led the research, said: “We have conclusively demonstrated that the early neurological and cognitive development of children with different ancestries is similar across diverse populations, providing that children and their parents have equal access to adequate nutrition, health care and education.”

This research provides valuable insight that could inform future policies and decision-making. Professor Michael Katz, Senior Vice-President Emeritus at the March of Dimes Foundation, USA, and President of the Oxford Maternal & Perinatal Health Institute, Green Templeton College, stated: “These findings have profound implications for international development policy because they make it clear that inequalities beginning during pregnancy have lifelong consequences for both individuals and countries. It also contradicts the concept that some ‘ethnic’ groups have a genetic advantage over others. Equitable access to universal education, health care and nutrition is, therefore, essential to any attempt to reach sustainable development goal targets globally.”

The attainment of neurodevelopmental milestones and associated behaviours in early childhood are likely universal, given adequate health, medical care, education, and nutrition. “The results clearly demonstrate that nurture is more important than nature with respect to human neurodevelopment,” adds Professor Stephen Kennedy, Head of the University’s Nuffield Department of Women’s & Reproductive Health, who jointly led the research.

The full paper, ‘Neurodevelopmental milestones and associated behaviours are similar among healthy children across diverse geographical locations,’ is published in the January 30 online edition of Nature Communications.

The INTERGROWTH-21st Project is funded by the Bill & Melinda Gates Foundation.