Elsevier

Obstetrics & Gynecology

Volume 98, Issue 6, December 2001, Pages 1080-1088
Obstetrics & Gynecology

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

https://doi.org/10.1016/S0029-7844(01)01567-8Get rights and content

Abstract

OBJECTIVE:

We examined the hypothesis that amniotic fluid (AF) infection and elevated cytokine concentrations may cause neonatal injury beyond that expected solely from prematurity.

METHODS:

The effects of exposure to AF infection and elevated cytokine concentrations were measured in 151 infants born to afebrile women in preterm labor with intact membranes at less than or equal to 34 weeks’ gestation. Amniotic fluid was collected by amniocentesis for culture and determination of tumor necrosis factor-α and interleukin-6. Cytokine concentrations, stratified by AF infection, were compared for three gestational age groups. We then examined the associations between a positive AF culture or elevated AF tumor necrosis factor-α 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-α concentration, or both. Amniotic fluid cytokine concentrations were significantly higher among women in preterm labor at less than or equal to 30 weeks, compared with 31–34 weeks. Nine of 11 infants who died at less than or equal to 24 hours of age had AF infection or elevated AF tumor necrosis factor-α. For the 140 surviving infants, AF infection and/or an elevated AF tumor necrosis factor-α was associated with respiratory distress syndrome (adjusted odds ratio [OR] 1.7), grade 3–4 intraventricular hemorrhage (adjusted OR 2.2), necrotizing enterocolitis (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 who have intact membranes and are initially afebrile, those exposed to AF bacteria or cytokines have more adverse neonatal outcomes than unexposed infants of similar birth weight.

Section snippets

Materials and methods

The study population included 151 women in premature labor and their infants born at less than or equal to 34 weeks’ gestation. Women were admitted to the University of Washington Medical Center, Swedish Medical Center, and Virginia Mason Medical Center in Seattle, Washington, between June 25, 1991, and June 30, 1997. All women provided written informed consent for study participation. The Institutional Review Board of each participating hospital approved the study protocol. Participants were

Results

Microorganisms were recovered from 30 (20%) of 151 AF specimens. Eight AF cultures grew single or mixed anaerobic organisms, and five cultures grew mixed aerobic and anaerobic flora. Ureaplasma urealyticum was isolated from four samples, Escherichia coli from three, Group B Streptococcus from two, Mycoplasma hominis from two, Candida albicans from two, and other aerobic isolates from four.

The AF tumor necrosis factor-α concentration was greater than 30 pg/mL in 21 (81%) of 26 culture-positive

Discussion

Infection of the AF appears to be primarily a fetal, rather than a maternal infection.6, 7 Considerable inflammatory response occurs to AF infection by 26 weeks’ gestation. The median concentration of tumor necrosis factor-α (726 pg/mL) at less than or equal to 26 weeks in infected AF is similar to that in the cerebral spinal fluid of children with meningitis (787 pg/mL) and in the abdominal fluid of adults with peritonitis (400 pg/mL).20, 21

Infants in the positive AF culture and the negative

References (29)

  • M.G Gravett et al.

    An experimental model for intraamniotic infection and preterm labor in rhesus monkeys

    Am J Obstet Gynecol

    (1994)
  • P.A Robertson et al.

    Neonatal morbidity according to gestational age and birth weight from five tertiary care centers in the United States, 1983 through 1986

    Am J Obstet Gynecol

    (1992)
  • M Hack et al.

    Effect of very low birth weight and subnormal head size on cognitive abilities at school age

    N Engl J Med

    (1991)
  • D.H Watts et al.

    The association of occult amniotic fluid infection with gestational age and neonatal outcome among women in preterm labor

    Obstet Gynecol

    (1992)
  • Cited by (91)

    • Leading causes of preterm delivery as risk factors for intraventricular hemorrhage in very preterm infants: results of the EPIPAGE 2 cohort study

      2017, American Journal of Obstetrics and Gynecology
      Citation Excerpt :

      We found no association between pPROM and IVH. This result differs from the increased risk of severe cerebral injuries previously shown in this context.41-43 One explanation for this inconsistency is that severe cerebral lesions usually group together as IVH grades III and IV as well as cystic periventricular leukomalacia.44

    View all citing articles on Scopus

    This work was supported by National Institutes of Health Grant AI-31071.

    View full text