title: Mortality and morbidity risks vary with birth weight standard deviation score in growth restricted extremely preterm infants.
abstract: OBJECTIVE
  To assess whether the mortality and morbidity risks vary with birth weight standard deviation score (BWSDS) in growth restricted extremely preterm infants.
  
  
  METHODS
  This was a multicenter retrospective cohort study using the database of the Neonatal Research Network of Japan and including 9149 infants born between 2003 and 2010 at <28 weeks gestation. According to the BWSDSs, the infants were classified as: <-2.0, -2.0 to -1.5, -1.5 to -1.0, -1.0 to -0.5, and ≥-0.5. Infants with BWSDS≥-0.5 were defined as non-growth restricted group.
  
  
  RESULTS
  After adjusting for covariates, the risks of mortality and some morbidities were different among the BWSDS groups. Compared with non-growth restricted group, the adjusted odds ratio (aOR) for mortality [aOR, 1.69; 95% confidence interval (CI), 1.35-2.12] and chronic lung disease (CLD) (aOR, 1.28; 95% CI, 1.07-1.54) were higher among the infants with BWSDS -1.5 to <-1.0. The aOR for severe retinopathy of prematurity (ROP) (aOR, 1.36; 95% CI, 1.09-1.71) and sepsis (aOR, 1.72; 95% CI, 1.32-2.24) were higher among the infants with BWSDS -2.0 to <-1.5. The aOR for necrotizing enterocolitis (NEC) (aOR, 2.41; 95% CI, 1.64-3.55) was increased at a BWSDS<-2.0.
  
  
  CONCLUSIONS
  Being growth restricted extremely preterm infants confer additional risks for mortality and morbidities such as CLD, ROP, sepsis and NEC, and these risks may vary with BWSDS.
authors.affiliation: Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Yamakawa
authors.affiliation: Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan. Electronic address: kitaba@med.showa-u.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Itabashi
authors.affiliation: Department of Neonatology, Maternal and Perinatal Center, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kusuda
mesh_terms: D000704:Analysis of Variance; D001724:Birth Weight; D005260:Female; D006801:Humans; D007223:Infant; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000453:epidemiology* / Q000401:mortality; D007564:Japan; D008297:Male; D054238:Perinatal Mortality; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*
keywords: Extremely preterm infants; Fetal growth restriction; Morbidity; Mortality; Small for gestational age