title: First-trimester maternal plasma cytokine levels, pre-pregnancy body mass index, and spontaneous preterm delivery.
abstract: OBJECTIVE
  To examine associations between first-trimester plasma cytokines and spontaneous preterm delivery (sPTD).
  
  
  METHODS
  A case-control study was nested within the Danish National Birth Cohort, a cohort of women with 101,042 pregnancies from 1997 to 2002 who were recruited during pregnancy and followed prospectively.
  
  
  METHODS
  Subjects included 107 women delivering singleton infants at 24-29 weeks, 353 at 30-33 weeks, 422 at 34-36 weeks, and 1,372 at > or =37 weeks.
  
  
  METHODS
  Maternal plasma interleukin (IL)-2, IL-6, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured at a median of eight weeks gestation using multiplex flow cytometry. Adjusted odds ratios (ORs) were obtained using polytomous logistic regression.
  
  
  METHODS
  sPTD categorized as: 24-29 weeks, 30-33 weeks, 34-36 weeks, and > or =37 weeks (controls).
  
  
  RESULTS
  Elevated TNF-alpha and GM-CSF were associated with an increased risk of delivery at 34-36 weeks. In underweight women, sPTD <34 weeks was associated with elevated (>75th percentile) IL-6 (OR=5.62, 95% confidence interval (CI): 1.73, 18.26) and TNF-alpha (OR=3.02, CI: 1.02, 8.91) compared with term delivery. Conversely, among obese women, elevated IL-2 (OR=0.30, CI: 0.11, 0.78) and TNF-alpha (OR=0.15, CI: 0.05, 0.47) were associated with a reduced risk of delivering at <34 weeks. Cytokines were not related to delivery at <34 weeks in normal-weight and overweight women.
  
  
  CONCLUSIONS
  These findings suggest that the association between first-trimester plasma cytokine levels and sPTD may depend on pre-pregnancy body mass index.
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: Allison Elizabeth
authors.initials: AE
authors.lastname: Curry
authors.forename: Poul
authors.initials: P
authors.lastname: Thorsen
authors.forename: Carolyn
authors.initials: C
authors.lastname: Drews
authors.forename: Diana
authors.initials: D
authors.lastname: Schendel
authors.forename: Kristin
authors.initials: K
authors.lastname: Skogstrand
authors.forename: William Dana
authors.initials: WD
authors.lastname: Flanders
authors.forename: David
authors.initials: D
authors.lastname: Hougaard
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
authors.forename: Ida
authors.initials: I
authors.lastname: Vogel
mesh_terms: D015992:Body Mass Index; D016022:Case-Control Studies; D016207:Cytokines / Q000097:blood*; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000097:blood; D006801:Humans; D007376:Interleukin-2 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D016015:Logistic Models; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood*; D047928:Premature Birth / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D016207:Cytokines; D007376:Interleukin-2; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor