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The predictive ability of small for gestational age classification for adverse perinatal outcomes : a systematic review of the INTERGROWTH-21st, NICHD, and WHO fetal growth charts Wang, Jeremy H.

Abstract

Fetal growth restriction (FGR) is a significant clinical concern in pregnancy due to its strong associations with morbidity and mortality. Several ultrasonographic fetal growth standards and references are in use; however, many have limited internal and external validity due to methodological flaws. In recent years, three high-quality charts based on large longitudinal cohort studies were published: the National Institute of Child Health and Human Development (NICHD), International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st), and World Health Organization (WHO) charts. We aimed to summarize the evidence on the predictive ability of small for gestational age (SGA) classification by each of these charts for adverse perinatal outcomes, in order to help inform decisions on chart adoption in clinical settings. MEDLINE, Embase, and CINAHL databases were searched for relevant publications. Outcomes of interest included neonatal SGA, neonatal intensive care unit (NICU) admission, and perinatal mortality, among others. Information on composite outcomes was also extracted. When appropriate, meta-analysis using a random-effects model was carried out to produce summary estimates of the DOR, LR+, and LR-. Seventeen publications were eligible for inclusion, involving a total of 56,706 pregnancies. Predictive ability for neonatal SGA of the INTERGROWTH-21st chart was moderate, whether by AC centile (AUCs 0.77-0.87, 10th centile DORs 4.8-27.4) or EFW centile (AUCs 0.55-0.90, 10th centile DORs 2.2-29.2). The NICHD chart appeared to perform similarly, but only two studies were available. Meta-analysis produced pooled DOR estimates of 9.6 and 13.2 for INTERGROWTH-21st 10th centile AC and 10th centile EFW, respectively, although significant heterogeneity between studies was observed. Prediction of other adverse perinatal outcomes by all charts was generally poor (most AUCs ≤ 0.6 and most 10th centile DORs ≤ 5). While these new fetal growth charts may be able to predict small size at birth, they are inadequate for the prediction of adverse outcomes such as NICU admission or mortality. This reinforces the need for FGR screening methods that are not based on fetal size.

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