The INTERGROWTH-21st fetal growth standards: toward the global integration of pregnancy and pediatric care

Abstract

The purpose of the INTERGROWTH-21 project was to develop international, prescriptive standards for fetal growth assessed by ultrasound and fundal height, preterm postnatal growth, newborn size and body composition, maternal weight gain, and infant development at the age of 2 years. Hence, we have produced, based on World Health Organization recommendations, the first comprehensive set of international standards of optimal fetal and newborn growth that perfectly match the existing World Health Organization child growth standards. Uniquely, the same population was followed up longitudinally from 9 weeks of fetal life to 2 years of age, with growth, health, and nutritional status assessment at 2 years supporting the appropriateness of the population for construction of growth standards. The resulting package of clinical tools allows, for the first time, growth and development to be monitored from early pregnancy to infancy. The INTERGROWTH-21 fetal growth standards, which are based on observing >4500 healthy pregnancies, nested in a study of >59,000 pregnancies from populations with low rates of adverse perinatal outcomes, show how fetuses should grow-rather than the more limited objective of past references, which describe how they have grown at specific times and locations. Our work has confirmed the fundamental biological principle that variation in human growth across different populations is mostly dependent on environmental, nutritional, and socioeconomic factors. We found that when mothers' nutritional and health needs are met and there are few environmental constraints on growth, <3.5% of the total variability of skeletal growth was due to differences between populations. We propose that not recognizing the concept of optimal growth could deprive the most vulnerable mothers and their babies of optimal care, because local growth charts normalize those at highest risk for growth restriction and overweight, and can be valuable for policymakers to ensure rigorous evaluation and effective resource allocation. We strongly encourage colleagues to join efforts to provide integrated, evidence-based growth monitoring to pregnant women and their infants worldwide. Presently, there are 23.3 million infants born small for gestational age in low- to middle-income countries according to the INTERGROWTH-21 newborn size standards. We suggest that misclassification of these infants by using local charts could affect the delivery of optimal health care.

Prediction of adverse perinatal outcome by fetal biometry: comparison of customized and population‐based standards

“…For example, the World Health Organization (WHO) growth standard customizes only by fetal sex, while the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) developed ethnicity‐specific charts without adjusting for other factors. In addition, the INTERGROWTH‐21 st project proposed a ‘one‐size‐fits‐all’ standard without customization, yet the decision not to adjust for fetal sex was based on ethical grounds. Similarly, the Fetal Medicine Foundation (FMF) proposed a non‐customized fetal growth standard by reconciling fetal weight and birth weight data in a multi‐ethnic population that included a large majority (69%) of white women.…”

Design and other methodological considerations for the construction of human fetal and neonatal size and growth charts

“…Standards are meant to be used internationally and therefore enable direct comparisons to be made across different populations at the population level. The existence and use of different references within a country pose challenges of comparing and evaluating public health policies …”

Fetal size standards to diagnose a small- or a large-for-gestational-age fetus

“…2 The investigators proposed that these charts represent “optimal fetal size,” regardless of ethnic origin. The investigators included patients from eight urban areas in Brazil, Italy, Oman, the United Kingdom, the United States, China, India, and Kenya.…”