Relationship between serum ferritin and proinflammatory markers in late pregnancy: An exploratory analysis from Cartagena, Colombia

Introduction: In a previous study, we identified an inverse relationship between adverse perinatal outcomes and iron status during late pregnancy of women recruited from a maternal hospital in Cartagena, Colombia. Some of these outcomes have also been linked to maternal inflammatory states. However, there is currently no clarity regarding the relationship between iron levels and proinflammatory markers during this period.

Objective: To estimate the relationship between inflammatory markers and serum ferritin in third-trimester pregnancies.

Materials and methods: Serum ferritin, hemoglobin, and proinflammatory cytokine levels were determined in women in Cartagena in their third trimester of pregnancy. We analyzed the relationship between ferritin levels and proinflammatory cytokines, as well as the relationship between serum ferritin, hemoglobin, and inflammatory cytokine levels with adverse perinatal outcomes.

Results: The levels of IL-6 were significantly associated with serum ferritin levels (β = 0.42, SE = 0.21, p = 0.04) but not with maternal age. Maternal serum ferritin had a positive weak correlation with the absolute number of lymphocytes and monocytes. Hemoglobin and maternal serum ferritin were weakly and inversely associated with birth weight. Serum ferritin but not IL-6 or IL-8 was associated with preterm birth.

Conclusions: We observed direct and mild associations of serum iron markers (serum ferritin, hemoglobin, and hematocrit) with lymphocyte counts. The inflammation marker, IL-6, was mildly associated with serum ferritin levels in late pregnancy. Women with elevated white blood cell counts and serum ferritin levels tended to have infants with lower birth weights. This fact suggests a potential involvement of iron in inflammatory processes during pregnancy, and conditions associated with inflammation in the final trimester may have adverse effects on perinatal outcomes.