Objective
To evaluate the hypothesis that cytokine levels are associated with miscarriage risk using serum samples collected before report of miscarriage. Design: A nested case-control study. Setting: Biospecimens from the multisite Collaborative Perinatal Project, University of Florida, laboratory assessment of interleukin (IL)-1 receptor antagonist, IL-1beta, IL-4, IL-6, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, thrombopoietin (TPO), and granulocyte colony-stimulating factor (G-CSF). Patient(s): Cases of miscarriage (n = 439) were matched to controls (n = 373) by gestational age at sample collection. Intervention(s): None. Main outcome measure(s): Miscarriage. Result(s): Increased risk of miscarriage was associated with elevated TPO (adjusted odds ratio [OR] 1.16, 95% confidence interval [CI] 1.00-1.36) and decreased G-CSF (adjusted OR 0.78, 95% CI 0.64-0.95). When analysis was restricted to samples collected more than 35 days before miscarriage, the effect of G-CSF was not observed (adjusted OR 0.96, 95% CI 0.72-1.28), whereas increased risk related to higher TPO remained.