[Review of the literature on intrauterine and birthweight charts]. / Revue de la littérature des courbes intra-utérines et de poids de naissance.

OBJECTIVES: To describe the main intrauterine and birthweight charts and review the studies comparing their performance for the identification of infants at risk of adverse perinatal outcomes. METHODS: We carried out a literature search using Medline and selected the charts most frequently cited in the literature, French charts and those recently published. RESULTS: Current knowledge on the association between mortality and morbidity and growth anomalies (small and large for gestational age) mostly relies on the use of descriptive charts which describe the weight distribution in unselected populations. Prescriptive charts, which describe ideal growth in low risk populations, have been constructed more recently. Few studies have evaluated whether the thresholds used to identify infants at risk with descriptive charts (such as the 3rd or the 10th percentile) are applicable to prescriptive charts. There is a large variability in the percentage of fetuses or newborns identified as being at risk by each chart, with from 3 to 25% having with a weight under the 10th percentile, regardless of whether descriptive or prescriptive charts are used. The sensitivity and specificity of antenatal screening for small or large for gestational age newborns depends on the chart used to derive estimated fetal weight percentiles. CONCLUSION: There is marked variability between intrauterine growth charts that can influence the percentage of infants identified as having abnormal growth. These results show that before the adoption of a growth chart, it is essential to evaluate whether it adequately describes the population and its performance for identifying of infants at risk because of growth anomalies.

Comparison of the performance of estimated fetal weight charts for the detection of small- and large-for-gestational age newborns with adverse outcomes: a French population-based study.

OBJECTIVE: To compare the performance of estimated fetal weight (EFW) charts at the third trimester ultrasound for detecting small- and large-for-gestational age (SGA/LGA) newborns with adverse outcomes. DESIGN: Nationally representative observational study. SETTING: French maternity units in 2016. POPULATION: 9940 singleton live births with an ultrasound between 30 and 35 weeks of gestation. METHODS: We compared three prescriptive charts (INTERGROWTH-21st, World Health Organization (WHO), Eunice Kennedy Shriver National Institute of Child Health and Human Development [NICHD]), four descriptive charts (Hadlock, Fetal Medicine Foundation, two French charts) and a French customised growth model (Epopé). MAIN OUTCOME MEASURES: SGA and LGA (birthweights <10th and >90th percentiles) associated with adverse outcomes (low Apgar score, delivery-room resuscitation, neonatal unit admission). RESULTS: 2.1% and 1.1% of infants had SGA and LGA and adverse outcomes, respectively. The sensitivity and specificity for detecting these infants with an EFW <10th and >90th percentile varied from 29-65% and 84-96% for descriptive charts versus 27-60% and 83-96% for prescriptive charts. WHO and French charts were closest to the EFW distribution, yielding a balance between sensitivity and specificity for SGA and LGA births. INTERGROWTH-21st and Epopé had low sensitivity for SGA with high sensitivity for LGA. Areas under the receiving operator characteristics curve ranged from 0.62 to 0.74, showing low to moderate predictive ability, and diagnostic odds ratios varied from 7 to 16. CONCLUSION: Marked differences in the performance of descriptive as well as prescriptive EFW charts highlight the importance of evaluating them for their ability to detect high-risk fetuses. TWEETABLE ABSTRACT: Choice of growth chart strongly affected identification of high-risk fetuses at the third trimester ultrasound.