The relationship between leukemoid reaction and perinatal morbidity, mortality, and chorioamnionitis in low birth weight infants

Objectives: Neonatal leukemoid reaction (NLR) is relatively rare and considered as a white blood cell (WBC) count >= 50 x 10(9)/l. The aim of this study was to investigate the association of NLR with neonatal morbidity and mortality and maternal chorioamnionitis in low birth weight infants. Methods: In this case-controlled retrospective study, the medical records of 1200 newborn infants with a birth weight <2500 g admitted to the neonatal unit over a period of 5 years were reviewed. The infants who developed features of NLR (n = 17, 1.4%) formed the study group, while the remainder without NLR, matched for gestational age and birth weight (n = 123), formed the control group. A chart review was performed and salient demographic, clinical, and laboratory data abstracted. A statistical analysis was subsequently performed on this data. Results: The mean WBC and absolute neutrophil counts of infants with NLR were significantly higher than those in the control group. The peak time of NLR was at 7.9 +/- 3.6 (interquartile range (IQR) 1-30) days and on average it improved within 4.1 +/- 1.95 (IQR 2-9) days. It was noted that those infants with NLR were mostly born by vaginal delivery and their mothers had a higher rate of early rupture of the membranes and chorioamnionitis. NLR was associated with a 4-fold increase in sepsis, 20-fold increase in intraventricular hemorrhage, 54-fold increase in bronchopulmonary dysplasia, and 6-fold increase in mortality. In the study group, those infants whose mothers had chorioamnionitis had a higher rate of early rupture of the membranes and they developed sepsis and intraventricular hemorrhage more often than those whose mothers did not have clinical chorioamnionitis. Conclusions: In low birth weight newborn infants, NLR is significantly associated with sepsis, intraventricular hemorrhage, bronchopulmonary dysplasia, and a high mortality rate. Also, those infants with NLR are more likely to be born to mothers with chorioamnionitis and they face sepsis and intraventricular hemorrhage more often. (C) 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.