Amniotic fluid infection, inflammation, and colonization in preterm labor with intact membranes

C. Andrew Combs, Michael Gravett, Thomas J. Garite, Durlin E. Hickok, Jodi Lapidus, Richard Porreco, Julie Rael, Thomas Grove, Terry K. Morgan, William Clewell, Hugh Miller, David Luthy, Leonardo Pereira, Michael Nageotte, Peter A. Robilio, Stephen Fortunato, Hyagriv Simhan, Jason K. Baxter, Erol Amon, Albert FrancoKenneth Trofatter, Kent Heyborne

Research output: Contribution to journalArticlepeer-review

147 Scopus citations


Objective The purpose of this study was to compare intraamniotic inflammation vs microbial invasion of the amniotic cavity (MIAC) as predictors of adverse outcome in preterm labor with intact membranes. Study Design Interleukin-6 (IL-6) was measured in prospectively collected amniotic fluid from 305 women with preterm labor. MIAC was defined by amniotic fluid culture and/or detection of microbial 16S ribosomal DNA. Cases were categorized into 5 groups: infection (MIAC; IL-6, ≥11.3 ng/mL); severe inflammation (no MIAC; IL-6, ≥11.3 ng/mL); mild inflammation (no MIAC; IL-6, 2.6-11.2 ng/mL); colonization (MIAC; IL-6, <2.6 ng/mL); negative (no MIAC; IL-6, <2.6 ng/mL). Results The infection (n = 27) and severe inflammation (n = 36) groups had similar latency (median, <1 day and 2 days, respectively) and similar rates of composite perinatal morbidity and mortality (81% and 72%, respectively). The colonization (n = 4) and negative (n = 195) groups had similar outcomes (median latency, 23.5 and 25 days; composite morbidity and mortality rates, 21% and 25%, respectively). The mild inflammation (n = 47) groups had outcomes that were intermediate to the severe inflammation and negative groups (median latency, 7 days; composite morbidity and mortality rates, 53%). In logistic regression adjusting for gestational age at enrollment, IL-6 ≥11.3 and 2.6-11.2 ng/mL, but not MIAC, were associated significantly with composite morbidity and mortality rates (odds ratio [OR], 4.9; 95% confidence interval [CI], 2.2-11.2, OR, 3.1; 95% CI, 1.5-6.4, and OR, 1.8; 95% CI, 0.6-5.5, respectively). Conclusion We confirmed previous reports that intraamniotic inflammation is associated with adverse perinatal outcomes whether or not intraamniotic microbes are detected. Colonization without inflammation appears relatively benign. Intraamniotic inflammation is not simply present or absent but also has degrees of severity that correlate with adverse outcomes. We propose the designation amniotic inflammatory response syndrome to denote the adverse outcomes that are associated with intraamniotic inflammation.

Original languageEnglish (US)
Pages (from-to)125.e1-125.e15
JournalAmerican journal of obstetrics and gynecology
Issue number2
StatePublished - Feb 2014


  • chorioamnionitis
  • intraamniotic infection
  • intraamniotic inflammation
  • microbial invasion of the amniotic cavity
  • morbidity
  • preterm birth
  • preterm labor

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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