title: Does gender affect neonatal hyperbilirubinemia in low-birth-weight infants?
abstract: BACKGROUND
  Neonatal mortality and morbidity are gender-biased in low-birth-weight (LBW) infants. The male disadvantage theory has been suggested to be responsible for these maturational differences.
  
  
  OBJECTIVE
  To examine the impact of gender on neonatal hyperbilirubinemia.
  
  
  METHODS
  A retrospective observational study. Data on all LBW infants admitted to George Washington University neonatal intensive care unit and surviving for >48 hrs from January 1992 to March 2003 were analyzed. Males and females were compared for gestational age, birth weight, race, Apgar scores at 1 and 5 mins, peak bilirubin levels, sepsis, and intraventricular hemorrhage (IVH). Significant differences were entered in a regression model to detect the influence of gender on bilirubin (Bili). Analysis was repeated after stratification of infants into: group A, <1000 g; group B, 1000-1499 g; and group C, 1500-2499 g.
  
  
  RESULTS
  A total of 840 infants were included in this study. When comparing males (n = 407) with females (n = 433), significant differences were detected in birth weight (1,539 +/- 541 vs. 1,428 +/- 549 g; p = .003), IVH (14.2% vs. 9%; p = .025), and Bili (10.1 +/- 3.0 vs. 9.2 +/- 2.8 mg%; p < .001). No differences were detected in gestational age, sepsis, or Apgar 1 and 5. Difference in Bili for the entire group remained significant in the regression model (regression coefficient [RC] = 0.79 +/- 0.22; p < .001). In subgroup analyses: group A Bili (8.4 +/- 2.3 vs. 8.0 +/- 2.0; p = .14) and group B Bili (9.0 +/- 2.1 vs. 9.2 +/- 2.2; p = .51) did not differ in bivariate or multivariate analyses. In group C, Bili was (11.3 +/- 3.1 vs. 10.1 +/- 3.3; p < .001) and remained the only significant difference in the regression model (RC = 1.19 +/- 0.37; p = .001).
  
  
  CONCLUSIONS
  Bili in LBW infants is significantly higher in males when compared with females. After stratification to birth weight subgroups, significance is retained in the 1500- to 2499-g group after logistic regression analysis. Bili levels in infants <1500 g are influenced more significantly by factors other than gender, such as sepsis and IVH.
authors.affiliation: Department of Neonatology, The Children's National Medical Center, Washington, DC, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Tioseco
authors.forename: Hany
authors.initials: H
authors.lastname: Aly
authors.forename: Josh
authors.initials: J
authors.lastname: Milner
authors.forename: Kantilal
authors.initials: K
authors.lastname: Patel
authors.forename: Ayman A E
authors.initials: AA
authors.lastname: El-Mohandes
mesh_terms: D001034:Apgar Score; D001724:Birth Weight; D002543:Cerebral Hemorrhage / Q000150:complications; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007567:Jaundice, Neonatal / Q000209:etiology*; D008297:Male; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000150:complications; D012737:Sex Factors