Aneurin Young1,2, Ed Andrews1, James Ashton3,4, Freya Pearson1, R Mark Beattie3, Mark J Johnson1,2.

Institution(s)

1. Department of Neonatal Medicine, Southampton Children’s Hospital, University Hospital Southampton NHS Foundation Trust

2. NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust and University of Southampton

3. Department of Paediatric Gastroenterology, Southampton Children’s Hospital, University Hospital Southampton NHS Foundation Trust

4. Department of Human Genetics and Genomic Medicine, University of Southampton

Introduction (include hypothesis)

British neonatal units typically track the growth of preterm infants using the Newborn Infant Close Monitoring (NICM) chart1. This is based on UK 1990 data and is constructed from cross-sectional measurements of preterm infants at birth. We have recently shown that postnatal growth failure is not inevitable in our cohort of preterm infants. We hypothesise that growth data from our cohort can be used to construct growth charts which will differ from previous efforts and describe good postnatal growth.

Methods (include source of funding and ethical approval if required)

The Growth Assessment of Preterm Infants (GAP) study is funded by the NIHR Southampton Biomedical Research Centre and has national REC approval. Infants born before 30 weeks completed gestation were recruited from one level 3 neonatal unit in the South of England. In the relevant arm of the study, infants had their weight, length and head circumference measured each week from birth until discharge from this neonatal unit. Weight data were processed using the LMS method1 and centile charts were produced. These charts were compared with pre-existing standard centile growth charts.

Results

212 infants were recruited and used for analysis (124 male, mean gestational age at birth: 27+1 weeks, mean birthweight: 930g). 1755 observations of weight were made (mean 8.3 observations per infant). Growth charts were constructed using the LMS function of the gamlss package (v5.1-3, Stasinopoulos et al, 2019) using R (R Core Team 2019, v3.5.3) within the RStudio ecosystem (RStudio, inc. v1.2.1335). Growth charts for weight were successfully generated separately for boys and girls. Generated centile curves differed from the NICM chart in that the variation at term corrected age was greater, with the lighter centiles at lower weights. The shape of centile curves also differed, with accelerated growth between 30 and 35 weeks gestation, and somewhat slower proportional growth before and after this period. Comparison with the Fenton Growth Reference and Intergrowth 21st data showed similar findings.

Conclusions

The LMS method can be used to construct growth charts reflecting early postnatal growth of preterm infants. Significant questions remain concerning the definition of optimal postnatal growth, appropriate methods to track this growth and the nutritional management required to achieve it.

References (include acknowledgement here if appropriate)

1. Cole TJ, Freeman JV, Preece MA. British 1990 growth reference centiles for weight, height, body mass index and head circumference fitted by maximum penalized likelihood. Stat Med. 1998 Feb 8;17(4):407-29. PubMed PMID: 9496720. 2. Andrews ET, Ashton JJ, Pearson F, Beattie RM, Johnson MJ. Early postnatal growth failure in preterm infants is not inevitable. Arch Dis Child Fetal Neonatal Ed. 2019 May;104(3):F235-F241