# Classification of very low birth weight infants as small for gestational age: International vs. national standards

## TL;DR

This study compares two standards for identifying small-for-gestational-age very low birth weight infants and finds they have similar outcomes.

## Contribution

The study evaluates concordance and clinical outcomes between two growth standards for classifying small-for-gestational-age infants.

## Key findings

- High concordance was found between the Carrascosa 2008 and INTERGROWTH-21 standards (Cohen’s kappa = 0.80).
- The INTERGROWTH-21 standard classified fewer infants as small-for-gestational-age compared to Carrascosa 2008.
- No significant differences in mortality or morbidity were observed between the two classification methods.

## Abstract

It is not precisely known whether the use of national (Carrascosa 2008) and international growth standards (INTERGROWTH-21) shows good concordance in classifying very low birth weight infants as small-for-gestational-age or whether with the same degree of morbidity and mortality. The aims of this study were a) to evaluate the concordance between small-for-gestational-age neonates weighing <1500 g classified using the national and international standards, and b) to compare the morbidity and mortality of small-for-gestational-age neonates classified by both standards.

A retrospective cohort study was conducted with very low birth weight infants. The concordance between the INTERGROWTH-21 and Carrascosa 2008 standards was analyzed, along with differences in gestational age, weight, medical requirements, morbidity, and mortality, among small-for-gestational-age neonates classified by both standards. Small-for-gestational-age was defined as a birth weight z score ≤ −1.28.

A total of 250 neonates weighing <1500 g, who were born between 26 and 36 weeks of gestation, were included. There was a high level of concordance in the classification of small-for-gestational-age between the two standards (Cohen’s kappa = 0.80, p < 0.001). A lower incidence was observed when the INTERGROWTH-21 standard was used (31.6%) compared to the Carrascosa 2008 standard (40.8%), p = 0.03. No significant differences were found in mortality or morbidity among neonates classified as small-for-gestational-age by both standards.

The Carrascosa 2008 and INTERGROWTH-21 standards classify small-for-gestational-age infants with comparable morbidity and mortality. We recommend the use of the INTERGROWTH-21 standard for its inclusion of multiple pregnancies, diverse ethnicities, and international comparability.