title: Interpregnancy Interval and Anti-inflammatory Cervical Cytokines among Women with Previous Spontaneous Preterm Birth.
abstract: OBJECTIVE
  Both history of spontaneous preterm birth (sPTB) and shorter interpregnancy intervals (IPIs) increase the risk of recurrent sPTB. Mechanisms underlying the association between IPI and recurrent sPTB are unknown. We have previously demonstrated that higher concentrations of cervical anti-inflammatory cytokines are a risk factor for sPTB and upper genital tract inflammation. Here, we examine the association between IPI and cervical anti-inflammatory cytokines among women with previous sPTB.
  
  
  METHODS
  A prospective cohort of 73 women with previous sPTB and cervical interleukins (IL-4, IL-10, and IL-13) measured at < 16 weeks. Using the published principal factor analysis, the anti-inflammatory (ANTI) score was calculated. From our previous work, higher ANTI scores increase the subsequent risk of sPTB. IPI was the time from the previous birth to the conception of current pregnancy. Confounders included education level, marital status, gonorrhea, chlamydia, body mass index, race, and cigarette smoking. IPI and ANTI score were analyzed using univariable and multivariable analyses.
  
  
  RESULTS
  There was a significant negative linear relation between IPI and ANTI score (β = -0.075, p = 0.017). This persisted after adjustment for confounders (p = 0.02). As IPI decreases by 1 month, the ANTI-score-associated risk of sPTB increases approximately by 4%.
  
  
  CONCLUSIONS
  Among women with previous sPTB, there was a significant negative linear relation between IPI and ANTI score.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee-Womens Hospital of the University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Raj
authors.initials: R
authors.lastname: Shree
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee-Womens Hospital of the University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Hyagriv N
authors.initials: HN
authors.lastname: Simhan
mesh_terms: D000328:Adult; D001721:Birth Intervals; D012634:Bodily Secretions / Q000737:chemistry*; D002584:Cervix Uteri / Q000737:chemistry*; D018932:Chemokine CCL2 / Q000032:analysis; D005260:Female; D006801:Humans; D016753:Interleukin-10 / Q000032:analysis; D018793:Interleukin-13 / Q000032:analysis; D015847:Interleukin-4 / Q000032:analysis; D007378:Interleukins / Q000032:analysis*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism; D011262:Pregnancy Trimester, Second / Q000378:metabolism; D047928:Premature Birth / Q000378:metabolism*; D011446:Prospective Studies; D018570:Risk Assessment; D055815:Young Adult
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D018793:Interleukin-13; D007378:Interleukins; D016753:Interleukin-10; D015847:Interleukin-4