Evaluation of the INTERGROWTH-21st project newborn standard for use in Canada

Abstract

ObjectiveTo evaluate the performance of the INTERGROWTH-21st Project newborn standard vis-a-vis the current Canadian birth weight-for-gestational age reference.MethodsAll hospital-based singleton live births in Canada (excluding Quebec) between 2002 and 2012 with a gestational age between 33 and 42 weeks were included using information obtained from the Canadian Institute for Health Information. Small- and large-for gestational age centile categories of the INTERGROWTH standard and Canadian reference were contrasted in terms of frequency distributions and rates of composite neonatal morbidity/mortality.ResultsAmong 2,753,817 singleton live births, 0.87% and 9.63% were <3rd centile and >97th centile, respectively, of the INTERGROWTH standard, while 2.27% and 3.55% were <3rd centile and >97th centile, respectively, of the Canadian reference. Infants <3rd centile and >97th centile had a composite neonatal morbidity/mortality rate of 46.4 and 12.9 per 1,000 live births, respectively, under the INTERGROWTH standard and 30.9 and 16.6 per 1,000 live births, respectively, under the Canadian reference. The INTERGROWTH standard <3rd centile and >97th centile categories had detection rates of 3.14% and 9.74%, respectively, for composite neonatal morbidity/ mortality compared with 5.48% and 4.60%, respectively for the Canadian reference. Similar patterns were evident in high- and low-risk subpopulations.ConclusionsThe centile distribution of the INTERGROWTH newborn standard is left shifted compared with the Canadian reference, and this shift alters the frequencies and neonatal morbidity/mortality rates associated with specific centile categories. Further outcome-based research is required for defining abnormal growth categories before the INTERGROWTH newborn standard can be used.

Adverse perinatal outcomes in immigrants: A ten‐year population‐based observational study and assessment of growth charts

“…Across immigrant subgroups, the incidence of SGA and LGA varied by about 2‐3 times depending on which chart was used. Similar to a Canadian study, we found that the distribution of the prescriptive INTERGROWTH‐21st growth standard (including only healthy mothers) was left‐shifted when compared to the descriptive Australia‐2012 reference (including all mothers). Hence, the incidence of SGA determined by the prescriptive chart was lower than that determined by the descriptive chart, while the incidence of LGA determined by the prescriptive chart was higher than that determined by the descriptive chart.…”

Composite neonatal morbidity indicators using hospital discharge data: A systematic review

“…Our algorithm identified 2037 references of which 17 included composite indicators corresponding to our eligibility criteria . For 5 of the 17 indicators, we included the original article or other sources which described the construction of the indicator, instead of the article from our search .…”

“…Indicators were used for a range of research questions with two principal purposes: to measure the burden of disease and to evaluate quality of care, in particular around delivery . Indicators were developed for all newborns, for low‐ or moderate‐risk births—defined as term or moderately preterm births—and for very preterm infants . One indicator in the second group assessed morbidity among moderately preterm twins .…”

“…International Classification of Disease (ICD) codes were used to define diagnoses, either using the 9th version (7 indicators), the 10th version (9 indicators), or providing both (1 indicator), as shown in Table 2. Thirteen indicators also included procedure codes, either to restrict diagnoses to those accompanied by a procedure or to include procedures reflecting morbidity which may not have been coded as a diagnosis . Most indicators were binary and unweighted, meaning that a newborn was classified as having morbidity if he or she had at least one of the component morbidities.…”

Variability in birthweight, birthweight charts, and adverse outcomes: Is the “right size” the right question?

“…From an epidemiologic perspective, their findings have implications for the estimation of risk of adverse outcomes associated with SGA and LGA. Differences in perinatal morbidity between the charts were interpreted by the authors as the product of a left shift in gestational age‐specific EFW centiles of the IG‐21 standard relative to the Australian references, similarly to a Canadian study that used IG‐21 newborn standards from 33 to 42 weeks’ gestation . The “left shift” in the birthweight distribution of the IG‐21 standards reflects a more internationally diverse sample compared with the “right shifted” Australian and Canadian reference populations, composed of a majority of births to better off native‐born parents of European descent.…”