Performance of different fetal growth charts in prediction of large-for-gestational age and associated neonatal morbidity in multiethnic obese population.

Objectives: To examine the performance of different fetal growth charts in the prediction of large-for-gestational age (LGA) and associated neonatal morbidity at term in a multiethnic, obese population.

Methods: This was a retrospective cohort study of 253 non-anomalous, singleton, term pregnancies that underwent serial third-trimester ultrasound scans due to maternal body mass index ≥ 35 kg/m . We compared the performance of the Hadlock, Gestation Related Optimal Weight (GROW), INTERGROWTH-21 (IG-21), World Health Organization (WHO) and Fetal Medicine Foundation (FMF) fetal growth reference charts in the prediction of LGA at birth, defined as birth weight > 90 percentile, and neonatal morbidity, defined as a composite of neonatal intensive care unit admission or 5-min Apgar score < 7.

Results: In the study population, 53 (20.9%) infants were born LGA, 27 (10.7%) experienced neonatal morbidity and nine (3.6%) were LGA with associated neonatal morbidity. The Hadlock and GROW charts showed similar performance in predicting LGA, with sensitivity of 66.0% for both and specificity of 82.5% and 83.5%, respectively. The positive likelihood ratios (LR+) were 3.77 (95% CI, 2.64-5.40) and 4.00 (95% CI, 2.77-5.78), respectively. The IG-21, WHO and FMF charts performed similarly and had higher sensitivity of about 85%, with specificity between 66% and 72%. LR+ was 2.74 (95% CI, 2.16-3.47), 2.50 (95% CI, 2.00-3.12) and 3.03 (95% CI, 2.36-3.89), respectively. All charts had high sensitivity for predicting neonatal morbidity associated with LGA, with LR+ ranging between 2.35 and 3.61.

Conclusions: In our multiethnic, obese population, all fetal growth charts performed well in predicting LGA and associated neonatal morbidity. However, the choice of fetal reference chart is likely to affect intervention rates. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.