Comparison of customized and cohort-based birthweight standards in identification of growth-restricted infants in GUSTO cohort study

Abstract

Background: The aim was to evaluate the ability of customized and cohort birthweight standards in discriminating intrauterine growth retardation (IUGR).

Methods: Birthweights (BWs) of GUSTO singleton infants born at gestational age (GA) 35–41 weeks were converted using two standards: (a) GUSTO cohort-based BW centile adjusted for GA and baby gender; (b) customized BW percentile calculator adjusted for maternal height and weight, race, parity, GA and gender. Infants were classified into three groups: (1) < 10th BW centile by customization– customized-SGA, (2) < 10th BW centile by GUSTO– GUSTO-SGA; and (3) > 10th BW centile by both standards – BOTH-non-SGA.

Results: Of the 1011 infant–mother dyads, 68 were customized-SGA and 104 were GUSTO-SGA, with concordance of 61% (n = 63) for SGA. While 5 (7%) of customized-SGA were not SGA by GUSTO-charts, 41 (39%) of GUSTO-SGA were not SGA by customized-charts. Customized-SGA had significantly the least growth in abdominal circumference (AC) and highest head circumference (HC): AC growth ratio between second and third trimester; and the lowest mean BW, ponderal index and placental weight than other groups.

Conclusion: Customized-SGA standard was a better discriminator of pathologic fetal growth based on AC growth. It improved strength of association with pathology and in our population reduced false positives (41/104 = 39%) in the assessment of SGA.

Keywords:

• Abdominal circumference
• customized birthweight centiles
• intra uterine growth restriction
• small for gestational age

Acknowledgements

The authors would like to thank the study subjects, their families, the GUSTO Study Group, Tuck Seng Cheng and Mor Jack Ng for their time and help.

Ethics approval

The study protocol was approved by Domain Specific Review Board of the Singapore National Healthcare Group and the Centralized Institutional Review Board of SingHealth. All participants gave their written informed consent.

Declaration of interest

This work is supported by the Translational Clinical Research (TCR) Flagship Program on Developmental Pathways to Metabolic Disease funded by the National Research Foundation (NRF) and administered by the National Medical Research Council (NMRC), Singapore – NMRC/TCR/004-NUS/2008.