Implications for Quantifying Early Life Growth Trajectories of Term-born Infants Using INTERGROWTH-21st Newborn Size Standards at Birth in Conjunction with World Health Organization Child Growth Standards in the Postnatal Period
Overview
Pediatrics
Public Health
Authors
Affiliations
Background: The INTERGROWTH-21st sex and gestational age (GA) specific newborn size standards (IG-NS) are intended to complement the World Health Organization Child Growth Standards (WHO-GS), which are not GA-specific. We examined the implications of using IG-NS at birth and WHO-GS at postnatal ages in longitudinal epidemiologic studies.
Objectives: The aim of this study was to quantify the extent to which standardised measures of newborn size and growth are affected when using WHO-GS versus IG-NS at birth among term-born infants.
Methods: Data from two prenatal trials in Bangladesh (n = 755) and The Gambia (n = 522) were used to estimate and compare size at birth and growth from birth to 3 months when using WHO-GS only ('WHO-GS') versus IG-NS at birth and WHO-GS postnatally ('IG-NS'). Mean length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ), and the prevalence of undernutrition (stunting: LAZ < -2SD; underweight: WAZ < -2SD; and microcephaly: HCAZ < -2SD) were estimated overall and by GA strata [early-term (37 -38 ), full-term (39 -40 ) and late-term (41 -43 )]. We used Bland-Altman plots to compare continuous indices and Kappa statistic to compare categorical indicators.
Results: At birth, mean LAZ, WAZ and HCAZ, and the prevalence of undernutrition were most similar among newborns between 39 and 40 weeks of GA when using WHO-GS versus IG-NS. However, anthropometric indices were systematically lower among early-term infants and higher among late-term infants when using WHO-GS versus IG-NS. Early-term and late-term infants demonstrated relatively faster and slower growth, respectively, when using WHO-GS versus IG-NS, with the direction and magnitude of differences varying between anthropometric indices. Individual-level differences in attained size and growth, when using WHO-GS versus IG-NS, were greater than 0.2 SD in magnitude for >60% of infants across all anthropometric indices.
Conclusions: Using IG-NS at birth with WHO-GS postnatally is acceptable for full-term infants but may give a misleading interpretation of growth trajectories among early- and late-term infants.
Perumal N, Ohuma E, Prentice A, Shah P, Al Mahmud A, Moore S Paediatr Perinat Epidemiol. 2022; 36(6):839-850.
PMID: 35570836 PMC: 9790258. DOI: 10.1111/ppe.12880.