Determination of birth-weight centile thresholds associated with adverse perinatal outcomes using population, customised, and Intergrowth charts: A Swedish population-based cohort study

• Published in: PLoS medicine 2019-09, Vol.16 (9), p.e1002902-e1002902
• Main Authors: Vieira, Matias C, Relph, Sophie, Persson, Martina, Seed, Paul T, Pasupathy, Dharmintra
• Format: Article
• Language: English
• Subjects: Adult; Age; Age Factors; Apgar score; Babies; Biology and Life Sciences; Birth Weight; Cesarean section; Charts; Child Development; Cohort analysis; Computer and Information Sciences; Customization; Epidemiology; Ethnicity; Female; Fetal development; Funding; Gestational Age; Health aspects; Health risk assessment; Health Status; Health Status Indicators; Hemorrhage; Heterogeneity; Homogeneity; Humans; Infant mortality; Infant, Newborn; Infant, Small for Gestational Age - growth & development; Infants; Life sciences; Medicine; Medicine and Health Sciences; Metabolic diseases; Morbidity; Mortality; Neonates; Newborn babies; Newborn infants; People and places; Perinatal Mortality; Population; Population studies; Population-based studies; Postpartum; Pregnancy; Pregnancy Outcome; Prenatal development; Reference Values; Registries; Risk Assessment; Risk Factors; Sepsis; Sex Factors; Stillbirth; Studies; Supervision; Sweden; Thresholds; Trauma; Ultrasonic imaging; Womens health
• ISSN: 1549-1676; 1549-1277; 1549-1676
• DOI: 10.1371/journal.pmed.1002902

Although many studies have compared birth-weight charts to determine which better identify infants at risk of adverse perinatal outcomes, less attention has been given to the threshold used to define small or large for gestational age (SGA or LGA) infants. Our aim was to explore different thresholds associated with increased risk of adverse perinatal outcomes using population, customised, and Intergrowth centile charts. This is a population-based cohort study (Swedish Medical Birth Registry), which included term singleton births between 2006 and 2015 from women with available data on first-trimester screening. Population, customised, and Intergrowth charts were studied. Outcomes included cesarean section, postpartum haemorrhage, severe perineal tear, Apgar score at 5 minutes, neonatal morbidity, and perinatal mortality. Odds for each outcome were assessed in intervals of 5 centiles of birth weight (reference being 40th-60th centiles) using logistic regression. Intervals of 5% of the population were also explored. Sensitivity for fixed false-positive rates (FPRs) was reported for neonatal outcomes. Data from 212,101 births were analysed. Mean age was 33 ± 5 years, 48% of women were nulliparous, and 80% were born in Sweden. Prevalence of SGA (90th centile) was 10.0%, 8.2%, and 25.1%, assessed using population, customised, and Intergrowth charts, respectively. In small infants, the risk of perinatal mortality was consistently increased below the 15th, 10th, and 35th birth-weight centiles for the respective charts (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.05-2.39, p = 0.03 for 10th-15th population centile; OR 2.54, 95% CI 1.74-3.71, p < 0.001 for 5th-10th customised centile; OR 1.81, 95% CI 1.07-3.04, p = 0.03 for 30th-35th Intergrowth centile). The strength of association with adverse perinatal outcomes was different between infants below the 5th birth-weight centile for each chart (OR 4.47, 95% CI 3.30-6.04, p < 0.001 for the population chart; OR 5.78, 95% CI 4.22-7.91, p < 0.001 for the customised chart; OR 10.74, 95% CI 7.32-15.77, p < 0.001 for the Intergrowth chart) but similar in the smallest 5% of the population (OR 4.34, 95% CI 3.22-5.86, p < 0.001 for the population chart; OR 5.23, 95% CI 3.85-7.11, p < 0.001 for the customised chart; OR 4.69, 95% CI 3.47-6.34, p < 0.001 for the Intergrowth chart). For a fixed FPR of 10%, different thresholds for each chart achieved simila