One foot, 7.5 inches. That’s the average height of a newborn baby born to a healthy, well-nourished mother, worldwide, according to a new study published yesterday in The Lancet, Diabetes and Endocrinology.
Across the globe, there are great disparities in babies’ average size at birth, and even within developed countries, babies born to some ethnic groups are more often small for their age. This has led some researchers to believe that there are genetic differences in infant growth among different populations. But this study, funded by The Bill and Melinda Gates Foundation, looked at nearly 60,000 pregnancies in the U.S., U.K., Brazil, Italy, China, India, Kenya, and Oman, and found very little difference in newborn size—if the babies were born in good conditions.
The mothers in the study were all “educated, affluent, healthy women with adequate nutritional status” between the ages of 18 and 35. They started prenatal care before 14 weeks of pregnancy, and lived and delivered their babies in areas where pollution, radiation, and other toxic substances were low or nonexistent. The researchers measured most of the babies after birth, but tracked a smaller subset’s growth in the womb with ultrasound measurements.