812: The relationship of second trimester serum progesterone, cytokine levels, and pregnancy outcome

Progesterone (P4) is an important anti-inflammatory agent during pregnancy. Serum cytokine values have been associated with adverse pregnancy outcome. Our goal was to assess the interrelationship between serum P4 concentration and serum cytokine levels. This study was a secondary analysis of a prospective, multicenter study evaluating cytokine expression in singletons. Patients were included if a serum P4 value could be obtained in the 2nd trimester and were followed into the 3rd trimester. Serum P4 was measured using an Immulite 1000. Patients had cytokine levels including IL-1ρ, IL-1β, IL-2, IL-6, IL-8, IL-10, TNFα, CRP and MMP8 measured using multiplex beadlyte assay on a Luminex IS-100 in both trimesters. Statistical associations between pro-and anti-inflammatory cytokines were calculated using univariate regression analysis. An adjusted regression analysis was also performed accounting for tobacco use by cotinine level. 109 patients underwent serum P4 measurement at a mean gestational age of 19.9 ± 1.5 weeks and 94 of these patients in the 3rd trimester. 23% were smokers and 13% delivered preterm. Univariate and adjusted analysis demonstrated a negative association between 2nd trimester serum P4 and IL-8, P=.0014. 3rd trimester P4 was negatively associated with MMP8, P< .001. The interval change in P4 concentration between trimesters was positively associated with the second trimester IL-8, P=.016, and negatively in the 3rd trimester with MMP-8, P=.005. Preterm birth was not significantly associated with the serum P4 in the 2nd or 3rd trimesters, nor was the interval change associated with preterm birth. However, the study was poorly powered for this outcome. Placental progesterone production is associated with alterations in the inflammatory milieu in the 2nd and 3rd trimesters. This relationship and any potential influence on preterm birth requires further study.