Growth, size of babies worldwide remarkably similar

Ana Langer poster

July 29, 2014 — Ana Langer, director of the Women and Health Initiative and Maternal Health Task Force (MHTF) at Harvard School of Public Health, says that new findings from an international study on fetal growth and birth length debunk longstanding beliefs that variations among fetal and infant sizes have something to do with genetics, race, or ethnicity.

The consortium that produced this study— the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st)—calls the new findings “landmark” on its website. Why is it so important to show that babies everywhere are born at roughly the same size?

Until now there has been no body of evidence that provided an answer to the question of whether fetal and infant growth was determined by maternal health and nutrition, genetics, race, or ethnicity. With this new study, the idea that some ethnicities and races may be genetically pre-determined to be smaller than others—which may have originated from current disparities in growth and size between and within countries—has been shown to be unfounded and untrue. Instead, the study found that fetal growth and birth length are incredibly similar around the world when babies are born to well-nourished, well-educated mothers. The new findings have, in short, provided us with a globally relevant understanding of what “normal” fetal and newborn growth is. The practical implication for pregnancy and newborn care is that the same growth standards can be used for babies all around the world. By confirming that a common optimal range of fetal growth and newborn size exists around the world, INTERGROWTH-21st has created a powerful epidemiological tool that will allow a valid comparison of the state of health of mothers and babies around the world. This study confirms that size at birth can be a sensitive indicator of the nutrition and wellbeing of mothers and the functionality of health systems. INTERGROWTH-21st has set the benchmark for fetal and newborn growth to which governments around the world and those of us working in maternal, newborn and child health can now strive to achieve.

What are the main objectives of the INTERGROWTH-21st Consortium and what role does MHTF play in its work?

INTERGROWTH-21st is a multidisciplinary network of more than 300 researchers and clinicians from 27 institutions in 18 countries—the largest collaborative venture in the field of perinatal health research. The primary objective of the INTERGROWTH-21st consortium was to compare growth in the fetal and newborn period in mothers at low risk of fetal growth problems due to socioeconomic, nutritional or medical issues in eight diverse populations around the world. The aim was to determine whether it was possible to create global growth standards from nine weeks gestation until birth, analogous to those widely adopted around the world for use in childhood. I serve as a member of the scientific advisory committee for the project. The MHTF helps to disseminate information from the INTERGROWTH-21st project to ensure the translation of these important findings, tools and resources into practice.

How optimistic are you that these new findings will catalyze real change in how babies and mothers are cared for around the world?

The challenges are huge. Too many women still don’t have access to institutional delivery of their babies and to care during pregnancy and postpartum. Health systems in low- and middle-income countries are weak and the mechanisms to incorporate new evidence and tools to improve the situation do not always exist. However, this consortium has produced truly amazing work. The public health message is clear: When mothers are healthy and well-nourished, newborns are healthy. These findings provide yet another persuasive piece of evidence as to the value of investing in girls, women, and mothers.

Karen Feldscher