Longitudinal changes in circulating concentrations of inflammatory markers throughout pregnancy: are there associations with diet and weight status?

The natural inflammation occurring during pregnancy can, under certain conditions, be associated with adverse pregnancy outcomes. This study aimed to (1) quantify changes in circulating concentrations of leptin, adiponectin, interleukin-6 (IL-6) and C-reactive protein (CRP) across trimesters of pregnancy, according to pre-pregnancy body mass index (ppBMI); and (2) examine the trimester-specific associations between the inflammatory markers' concentrations, a Mediterranean diet score (MDS) and the dietary inflammatory index (DII). We measured leptin, adiponectin and IL-6 by ELISA and CRP by high-sensitivity immunonephelometry, in blood samples from 79 pregnant women (age: 32.1 ± 3.7 years; ppBMI: 25.7 ± 5.8 kg/m²). Three Web-based 24-h recalls were completed at each trimester and used to compute the MDS and the DII. CRP concentrations remained stable across trimesters, whereas concentrations of leptin and IL-6 increased, and adiponectin concentrations decreased (p < 0.001). Changes in leptin and adiponectin concentrations also differed according to ppBMI categories (p < 0.05). As for the dietary scores, the only significant association was observed in the second trimester between leptin concentrations and the MDS (r = -0.26, p < 0.05). In conclusion, ppBMI and the progression of pregnancy itself probably supplant the potential associations between diet and the inflammation occurring during that period. Novelty: Circulating leptin and IL-6 concentrations increased across trimesters whereas CRP was stable, and adiponectin decreased. Variations in circulating leptin and adiponectin concentrations differed by ppBMI categories. Very few associations were observed between dietary scores and inflammatory markers.