Maternal serum ADMA is not associated with proinflammatory cytokines or C-reactive protein during normal pregnancy

Normal pregnancy is associated with changes in the immune system. We studied whether asymmetrical dimethylarginine (ADMA) is associated with this immune system change by assaying high sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). The cytokine and dimethylarginine serum concentrations were determined from women with normal pregnancy (n = 77) and healthy non-pregnant controls (n = 61) matched for age and smoking status as a part of a large population-based, prospective cohort study conducted in Finland. The hsCRP levels were significantly elevated in the second (P = 0.016) and third trimesters (P = 0.001) of pregnancy compared to the levels of non-pregnant women. IL-6 levels were significantly higher in the third trimester (P = 0.029) of pregnancy than in non-pregnant state. TNF-α concentrations did not change significantly during pregnancy. ADMA and SDMA concentrations were significantly lower during pregnancy compared to the levels of non-pregnant women (P < 0.001). There was no significant association between ADMA and inflammation markers regardless of the elevated serum concentrations of hsCRP and IL-6 in the third trimester of normal pregnancy. These results suggest that maternal systemic ADMA and SDMA concentrations are more likely to become decreased due to the hemodilution and increased renal clearance than being directly influenced by the change of cytokines during pregnancy.