Amniotic fluid infection, cytokines, and adverse outcome among infants at 34 weeks' gestation or less

Objective: We examined the hypothesis that amniotic fluid (AF) infection an d elevated cytokine concentrations may cause neonatal injury beyond that ex pected solely from prematurity. Methods: The effects of exposure to AF infection and elevated cytokine conc entrations were measured in 151 infants born to afebrile women in preterm l abor with intact membranes at less than or equal to 34 weeks' gestation. Am niotic fluid was collected by amniocentesis for culture and determination o f tumor necrosis factor-alpha and interleukin-6. Cytokine concentrations, s tratified by AF infection, were compared for three gestational age groups. We then examined the associations between a positive AF culture or elevated AY tumor necrosis factor-alpha concentration and adverse neonatal outcomes , adjusted for birth weight. Results. Amniotic fluid from 45 (30%) of 151 pregnancies had microorganisms , an elevated tumor necrosis factor-alpha concentration, or both. Amniotic fluid cytokine concentrations were significantly higher among women in pret erm labor at less than or equal to 30 weeks, compared with 31-34 weeks. Nin e of 11 infants who died at less than or equal to 24 hours of age had AF in fection or elevated AF tumor necrosis factor-alpha. For the 140 surviving i nfants, AF infection and/or an elevated AF tumor necrosis factor-a was asso ciated with respiratory distress syndrome (adjusted odds ratio [OR] 1.7), g rade 3-4 intraventricular hemorrhage (adjusted OR 2.2), necrotizing enteroc olitis (adjusted OR 1.8), and multiple organ dysfunction (adjusted OR 3.0). Conclusion: Among infants born at less than or equal to 34 weeks to women w ho have intact membranes and are initially afebrile, those exposed to AF ba cteria or cytokines have more adverse neonatal outcomes than unexposed infa nts of similar birth weight. (Obstet Gynecol 2001;98: 1080-8. (C) 2001 by t he American College of Obstetricians and Gynecologists.).