Adjusting growth standards for fetal sex improves correlation of small babies with stillbirth and adverse perinatal outcomes: A state-wide population study

Objective: Identify the proportion of infants reclassified if sex-specific birthweight charts were used, and if this reclassification has an impact on the correlation between birthweight centile and adverse perinatal outcome. Design: Retrospective cohort study Setting: Victoria, Australia. Population: All infants born from 2005-2015 (529,261) Methods: We applied GROW centiles, either adjusted or unadjusted for fetal sex. We compared proportions of small for gestational age (SGA, <10th centile) infants, then the populations of males considered small only by sex-specific charts and females considered small only by unadjusted charts. Main Outcome Measures: Stillbirth, combined perinatal mortality, NICU admissions, Apgars <7 at 5 minutes, emergency caesarean sections. Results: Of those <10th centile by unadjusted charts, 39.6% were male, and 60.5% female. Using sex-specific charts, 50.3% <10th centile were male and 49.7% female. 9,449 (19.2%) females that were SGA according to unadjusted charts were appropriate for gestational age (AGA,>10th-<90th centile) using sex-specific charts. These reclassified newborn females were not at increased risk of adverse outcomes compared with an AGA infant, but were at increased risk of being iatrogenically delivered for suspected growth restriction (RR 4.90, 95%CI 4.39–5.48). 8,048 male infants were reclassified as SGA by sex-specific charts (25% SGA increase). Compared with AGA infants, these reclassified male newborns were at greater risk of stillbirth (RR 1.94, 95%CI 1.30-2.90) and all other adverse perinatal outcomes. Conclusions: Sex-specific growth standards classify a new high-risk cohort of male infants as SGA, and exclude a cohort of females, whose risk is no greater than appropriately grown infants.

Population Structure of Nation-Wide Rice in Thailand

Background Thailand is a country with large diversity in rice varieties due to its rich and diverse ecology. In this paper, 300 rice accessions from all across Thailand were sequenced to identify SNP variants allowing for the population structure to be explored. Results The result of inferred population structure from admixture and clustering analysis illustrated strong evidence of substructure in each geographical region. The results of phylogenetic tree, PCA analysis, and machine learning on population identifying SNPs also supported the inferred population structure. Conclusion The population structure inferred in this study contains five subpopulations that tend to group individuals based on location. So, each subpopulation has unique genetic patterns, agronomic traits, as well as different environmental conditions. This study can serve as a reference point of the nation-wide population structure for supporting breeders and researchers who are interested in Thai rice.

O016 Exploring the drivers of geographic variation for paediatric tonsillectomy and adenoidectomy

Introduction Tonsillectomy and/or adenoidectomy (A/T) is first-line treatment for paediatric obstructive sleep apnoea. Provision of A/T is of critical interest to sleep medicine practitioners. Geographic variation of A/T has been described since the 1930s, but no studies have investigated the reasons behind it. This study aimed to describe the geographical distribution of paediatric A/T and investigate area-level factors associated with this variation. Methods Linked administrative datasets captured a complete state-wide population of paediatric A/T performed between 2010 and 2015. Surgery data were collapsed by patient residence to the level of Local Government Area. Regression models were used to investigate the association between likelihood of surgery and area-level factors. Results There was a 10.2-fold difference in A/T rates across the state, with higher rates more common in regional than metropolitan areas. Area-level factors associated with geographic variation that increased the likelihood of A/T were a higher proportion of children aged 5–9 years (IRR 1.07, 95%CI 1.01–1.14, P=0.03), while a higher proportion with low English-language proficiency (IRR 0.95, 95%CI 0.90–0.99, P=0.03) decreased the likelihood of A/T. In a sub-population of public sector surgeries, low maternal educational attainment increased the likelihood of A/T (IRR 1.09, 95%CI 1.02–1.16, P&lt;0.001) and longer surgical waiting time reduced it (IRR 0.996, 95%CI 0.99273–0.99997, P=0.048). Discussion Significant variation in surgery rates exist by geographical area state-wide, with factors analysed having significant impacts. These findings suggest that improved surgical access and better community understanding of the indications for A/T could decrease geographic variation.