Fitness of INTERGROWTH-21st birth weight standards for Chinese-ethnicity babies

Area of Science:

• Perinatal medicine
• Neonatology
• Public health

Background:

• Accurate fetal growth assessment is crucial for identifying infants at risk of adverse outcomes.
• Existing international growth charts may not be universally applicable across diverse ethnic populations.
• The INTERGROWTH-21st Project provides global fetal and newborn growth standards.

Purpose of the Study:

• To evaluate the performance of the INTERGROWTH-21st (INTERGROWTH21) birth weight standards in ethnic Chinese neonates.
• To compare INTERGROWTH21 with a local Hong Kong reference (FOK2003) for assessing fetal growth.
• To determine the fitness of INTERGROWTH21 for classifying small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants.

Main Methods:

• A population-based analysis of territory-wide birth data from Hong Kong public hospitals (2006-2017).
• Inclusion of live births between 24 and 42 complete weeks of gestation.
• Comparison of INTERGROWTH21 and FOK2003 based on SGA/LGA proportions, mean birth weight Z-scores, and prediction of SGA-related complications.

Main Results:

• Analysis included 488,896 infants. INTERGROWTH21 showed mean birth weight Z-scores closer to zero for neonates born <33 weeks' gestation.
• INTERGROWTH21 classified fewer infants as SGA (8.3% vs 9.6%) and LGA (6.6% vs 7.9%) compared to FOK2003.
• FOK2003 demonstrated a greater area under the receiver operating characteristic curve for predicting SGA-related complications (0.674) than INTERGROWTH21 (0.658).

Conclusions:

• The INTERGROWTH21 standards performed less effectively than the local FOK2003 reference for ethnic Chinese babies, particularly for preterm infants (<33 weeks' gestation).
• Both references exhibited poor performance in classifying extremely preterm infants.
• A more robust growth chart, based on larger, appropriately selected infant samples, is necessary for improved accuracy in this population.