Identification of the optimal growth charts for use in a preterm population: An Australian state-wide retrospective cohort study

Abstract

BackgroundPreterm infants are a group at high risk of having experienced placental insufficiency. It is unclear which growth charts perform best in identifying infants at increased risk of stillbirth and other adverse perinatal outcomes. We compared 2 birthweight charts (population centiles and INTERGROWTH-21st birthweight centiles) and 3 fetal growth charts (INTERGROWTH-21st fetal growth charts, World Health Organization fetal growth charts, and Gestation Related Optimal Weight [GROW] customised growth charts) to identify which chart performed best in identifying infants at increased risk of adverse perinatal outcome in a preterm population.Methods and findingsWe conducted a retrospective cohort study of all preterm infants born at 24.0 to 36.9 weeks gestation in Victoria, Australia, from 2005 to 2015 (28,968 records available for analysis). All above growth charts were applied to the population. Proportions classified as <5th centile and <10th centile by each chart were compared, as were proportions of stillborn infants considered small for gestational age (SGA, <10th centile) by each chart. We then compared the relative performance of non-overlapping SGA cohorts by each chart to our low-risk reference population (infants born appropriate size for gestational age [>10th and <90th centile] by all intrauterine charts [AGAall]) for the following perinatal outcomes: stillbirth, perinatal mortality (stillbirth or neonatal death), Apgar <4 or <7 at 5 minutes, neonatal intensive care unit admissions, suspicion of poor fetal growth leading to expedited delivery, and cesarean section. All intrauterine charts classified a greater proportion of infants as <5th or <10th centile than birthweight charts. The magnitude of the difference between birthweight and fetal charts was greater at more preterm gestations. Of the fetal charts, GROW customised charts classified the greatest number of infants as SGA (22.3%) and the greatest number of stillborn infants as SGA (57%). INTERGROWTH classified almost no additional infants as SGA that were not already considered SGA on GROW or WHO charts; however, those infants classified as SGA by INTERGROWTH had the greatest risk of both stillbirth and total perinatal mortality. GROW customised charts classified a larger proportion of infants as SGA, and these infants were still at increased risk of mortality and adverse perinatal outcomes compared to the AGAall population. Consistent with similar studies in this field, our study was limited in comparing growth charts by the degree of overlap, with many infants classified as SGA by multiple charts. We attempted to overcome this by examining and comparing sub-populations classified as SGA by only 1 growth chart.ConclusionsIn this study, fetal charts classified greater proportions of preterm and stillborn infants as SGA, which more accurately reflected true fetal growth restriction. Of the intrauterine charts, INTERGROWTH classified the smallest number of preterm infants as SGA, although it identified a particularly high-risk cohort, and GROW cus...

FIGO (International Federation of Gynecology and Obstetrics) initiative on fetal growth: Best practice advice for screening, diagnosis, and management of fetal growth restriction

“…That is, identifying the chart that when applied to the local population yields weight percentiles that follow a normal distribution centered at approximately the 50th percentile, and identifies approximately 10% of the low-risk population as being below the 10th percentile and above the 90th percentile, and approximately 5% of the population as being below the 5th percentile and above the 95th percentile. An example of this approach is provided in Figure 3; (2) outcome-based validation: finding the chart for which the diagnosis of SGA has the best predictive value for adverse outcomes related to FGR.. 211,221 While this approach seems compelling, interpretation of the predictive value of the different charts for adverse outcomes may be challenging, as there is a trade-off between detection rate and false positive rate for adverse outcomes. 221 (Figure 4).…”

Earlier Nutrient Fortification of Breastmilk Fed LBW Infants Improves Jaundice Related Outcomes

“…Of particular concern is that Intergrowth-21st charts underestimate the rate of SGA compared to Fenton charts, which is of relevance in a lower socioeconomic community such as is the case with our study [15]. In our own state of Victoria, a recent statewide survey of 28000 births concluded that "intrauterine charts appear to be the most sensitive in the detection of SGA infants at increased risk of adverse perinatal outcomes" [16]. On evaluation, we opted to remain with the 2013 Fenton growth charts as we are currently using these on a day to day basis in our SCN and our previously published study [11] used 2013 Fenton growth charts-thus allowing a valid comparison of results with this study.…”

The pitfalls of using birthweight centile charts to audit care

“…We found that the normative INTERGROWTH-21 st birthweight distribution is left-shifted compared to Australian population centiles, yielding a much lower proportion of babies with birthweight <3 rd and <10 th centile. While this will identify the most severely growth restricted infants, thereby minimising the number of constitutionally small babies within the lower centiles, it will come at the expense of missing many growth restricted babies at high risk of adverse outcome [26,27]. We also showed that, when using a prescriptive birthweight standard, the effect of targeted earlier delivery of FGR led to almost total elimination of babies with birthweight <3 rd centile over time at late term gestations.…”