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Updated: Aug 19, 2026
Biochemical Measurement of Neonatal Hypoxia
Published on: August 24, 2011
Does gender affect neonatal hyperbilirubinemia in low-birth-weight infants?
Jennifer A Tioseco1, Hany Aly, Josh Milner
1Department of Neonatology, The Children's National Medical Center, Washington, DC, USA.
Insights
Male low-birth-weight infants have higher bilirubin levels than females. This gender difference in neonatal hyperbilirubinemia is significant in infants weighing 1500-2499g but not in smaller infants.
Area of Science:
- Neonatology
- Pediatric Endocrinology
Background:
- Neonatal mortality and morbidity exhibit gender bias in low-birth-weight (LBW) infants, potentially due to the male disadvantage theory.
- Maturational differences between male and female LBW infants contribute to gender-specific health outcomes.
Purpose of the Study:
- To investigate the influence of gender on the incidence and severity of neonatal hyperbilirubinemia in LBW infants.
- To determine if gender is an independent risk factor for elevated bilirubin levels in neonates.
Main Methods:
- Retrospective observational study of 840 LBW infants admitted to a neonatal intensive care unit (NICU) between 1992 and 2003.
- Comparison of males and females on gestational age, birth weight, Apgar scores, sepsis, intraventricular hemorrhage (IVH), and peak bilirubin (Bili) levels.
- Logistic regression analysis was used to assess the impact of gender on Bili, with stratification by birth weight subgroups (<1000g, 1000-1499g, 1500-2499g).
Main Results:
- Overall, male LBW infants (n=407) had significantly higher peak bilirubin levels (10.1 ± 3.0 mg%) compared to females (n=433, 9.2 ± 2.8 mg%; p < .001).
- Gender was a significant predictor of higher Bili in the overall cohort (regression coefficient [RC] = 0.79 ± 0.22; p < .001).
- In subgroup analysis, significantly higher Bili levels in males were only observed in the 1500-2499g birth weight group (11.3 ± 3.1 vs. 10.1 ± 3.3 mg%; p < .001), and this remained significant after regression analysis (RC = 1.19 ± 0.37; p = .001).
Conclusions:
- Male gender is associated with significantly higher bilirubin levels in low-birth-weight infants.
- The influence of gender on hyperbilirubinemia is weight-dependent, primarily affecting larger LBW infants (1500-2499g).
- In smaller LBW infants (<1500g), factors such as sepsis and intraventricular hemorrhage (IVH) have a more significant impact on bilirubin levels than gender.
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.
Design/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.
