International Fetal and Newborn Growth Consortium for the 21st Century- Written evidence (PRT0040)
The International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st)
Nuffield Department of Women’s and Reproductive Health and The Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford
Subject: Improving health outcomes in preterm infants by standardising size assessment at birth, feeding practices and measurement of postnatal growth
Summary
The INTERGROWTH-21st Consortium, that is dedicated to global maternal and perinatal health research and policy implementation, welcomes the opportunity to contribute to the House of Lords Preterm Birth Committee's inquiry. We advocate for the adoption within the NHS of the international INTERGROWTH-21st standards for assessing newborn size at birth and the postnatal growth of preterm infants that complement the WHO Child Growth Standards.
What are the INTERGROWTH-21st standards?
INTERGROWTH-21st is a multidisciplinary network of more than 300 scientists and clinicians from 27 institutions in 18 countries worldwide, coordinated by the University of Oxford. We are dedicated to preventing the deaths of millions of small vulnerable newborns that occur as a result of preterm birth and/or poor intrauterine growth.
To meet this goal, we built upon the WHO Multicentre Growth Reference Study (MGRS), which in 2006 released the WHO Child Growth Standards, age-based charts for height, weight, and body mass index, for monitoring and assessing the growth of children from age 0 to 5 years of age.1 The WHO Child Growth Standards were implemented in the UK in 2009 (replacing the UK1900 reference) on the recommendation of the Royal College of Paediatrics and Child Health and the Scientific Advisory Committee on Nutrition.
The WHO Child Growth Standards are based on infants born at term (grouped as one entity) posing the question how to measure preterm babies at birth and postnatally. To close this knowledge gap, INTERGROWTH-21st published, in a set of papers in Lancet journals between 2014 and 2016,2-6 new sex and gestational age specific birth size standards for term, preterm and very preterm newborns, as well as postnatal growth standards to monitor preterm newborns, which overlap with the WHO Child Growth Standards by 64 weeks postmenstrual age.
INTERGROWTH-21st Newborn Size Standards complementing the WHO Child Growth Standards
Evidence-base supporting the use of the INTERGROWTH-21st Standards
The methodology that produced the INTERGROWTH-21st standards overcame the limitations of previous preterm charts.7,8 Firstly, the project followed the same participants from <14 weeks’ gestation until 2 years of age, which allowed all measures to be compared within the same population (as opposed to studies using measures from different populations at different times).
Secondly, the project produced prescriptive standards, as opposed to the available references. In brief, previously used references describe how fetuses, newborns, or children have grown at a particular place and time (even decades ago). Standards, on the other hand, define how preterm infants should grow under optimal conditions considering their degree of maturation. The concept of using prescriptive standards such as the WHO Child Growth Standards, which are perfectly complemented by the INTERGROWTH-21st standards, is well established internationally.
Thirdly, the INTERGROWTH-21st preterm postnatal growth standards have important features that distinguish them from existing charts, e.g. the use of human milk to achieve optimal postnatal growth and the availability of morbidity data. Even more importantly is that the standards are derived from 1759 repeated measures taken in the follow-up postnatal period to 64 weeks, as opposed to many charts in current use that are not based on longitudinal data. Some charts are even based on the belief that preterm newborns should follow fetal growth patterns. However, we believe the use of such charts promotes rapid weight gain during the first months of life and may be a critical contributor to obesity in later life.9,10 To facilitate best practice, the INTERGROWTH-21st Consortium, in collaboration with The Global Health Network and the University of Oxford, has made available an online course on “Preterm infant feeding and growth monitoring: Implementation of the INTERGROWTH-21st protocol”.
The multicentre, population-based nature of the INTERGROWTH-21st Project (eight urban sites in Brazil, China, India, Italy, Kenya, Oman, UK and USA), involving healthy pregnant women receiving evidence-based antenatal care, has dispelled the erroneous notion that there are substantive biological or genetic reasons why certain ethnic groups have high preterm birth rates.3 In fact, the overall preterm birth rate of 4.9% we reported in the INTERGROWTH-21st Project, with a very low rate of babies born between 24 and 33 weeks’ gestation, is a public health message for all countries. This is especially important for the UK as 19 ethnic groups were identified in the 2021 population census contributing to the well-documented inequities in maternity care and outcomes.
Current use of the INTERGROWTH-21st standards internationally and in the UK
WHO and the Centers for Disease Control and Prevention (CDC) have since the 2015 Zika epidemic recommended the use of the INTERGROWTH-21st standards to monitor newborn size at birth.11,12 At the international level, many countries have implemented the use of either the fetal, newborn or preterm postnatal growth standards, such as Argentina, Brazil, France, Nigeria and Sri Lanka.
In 2023, a collaboration between the Lancet and BJOG launched the Small Vulnerable Newborn (SVN) concept, a new framework to bring together the three conditions of preterm birth, small for gestational age (SGA), and low birthweight (LBW) to present a unified front in the fight towards every newborn reaching their highest attainable standard of health.13 The global estimates of the prevalence of SVNs are based on the INTERGROWTH-21st newborn size standards.14,15
In contrast, in the UK, national implementation has not occurred: the INTERGROWTH-21st standards have only been implemented in a few NHS Trusts, such as St. George’s University Hospitals and University Hospitals Leicester NHS Trusts. Tommys, a UK charity researching the causes of preterm birth, and the developer of the My Prem Baby app to track fetal, newborn and postnatal growth of preterm infants – are also using the INTERGROWTH-21st standards in all their material.
References
1. de Onis M, Garza C, Onyango AW, Martorell R. WHO Child Growth Standards. Acta Paediatr Suppl 2006; 450: 1-101.
2. Villar J, Cheikh Ismail L, Victora CG, et al. International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project. Lancet 2014; 384(9946): 857-68.
3. Villar J, Papageorghiou AT, Pang R, et al. The likeness of fetal growth and newborn size across non-isolated populations in the INTERGROWTH-21st Project: the Fetal Growth Longitudinal Study and Newborn Cross-Sectional Study. Lancet Diabetes Endocrinol 2014; 2(10): 781-92.
4. Villar J, Giuliani F, Bhutta ZA, et al. Postnatal growth standards for preterm infants: the Preterm Postnatal Follow-up Study of the INTERGROWTH-21st Project. Lancet Glob Health 2015; 3(11): e681-91.
5. Villar J, Giuliani F, Fenton TR, et al. INTERGROWTH-21st very preterm size at birth reference charts. Lancet 2016; 387(10021): 844-5.
6. Papageorghiou AT, Ohuma EO, Altman DG, et al. International standards for fetal growth based on serial ultrasound measurements: the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project. Lancet 2014; 384(9946): 869-79.
7. Giuliani F, Cheikh Ismail L, Bertino E, et al. Monitoring postnatal growth of preterm infants: present and future. Am J Clin Nutr 2016; 103(2): 635S-47S.
8. Villar J, Giuliani F, Barros F, et al. Monitoring the Postnatal Growth of Preterm Infants: A Paradigm Change. Pediatrics 2018; 141(2).
9. Villar J, Giuliani F, Figueras-Aloy J, et al. Growth of preterm infants at the time of global obesity. Arch Dis Child 2018.
10. Hirst JE, Villar J, Papageorghiou AT, Ohuma E, Kennedy SH. Preventing childhood obesity starts during pregnancy. Lancet 2015; 386(9998): 1039-40.
11. Assessment of infants with microcephaly in the context of Zika virus: Interim guidance. 2016. WHO_ZIKV_MOC_16.3_eng.pdf.
12. WHO. Screening, assessment and management of neonates and infants with complications associated with Zika virus exposure in utero: Interim guidance update. 30 August 2016.
13. Ashorn P, Ashorn U, Muthiani Y, et al. Small vulnerable newborns-big potential for impact. Lancet 2023; 401(10389): 1692-706.
14. Suarez-Idueta L, Yargawa J, Blencowe H, et al. Vulnerable newborn types: Analysis of population-based registries for 165 million births in 23 countries, 2000-2021. BJOG 2023 online ahead of print.
15. Lawn JE, Ohuma EO, Bradley E, et al. Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting. Lancet 2023; 401(10389): 1707-19.
27 March 2024