Pregestational overweight and obesity are connected with differences in gut microbiota composition and systemic inflammation at third trimester

The obesity epidemic is a global challenge, and the velocity of propagation is high in the population at reproductive age. Overweight and obesity during pregnancy have been associated with high birth weight and increased risk of childhood obesity, reinforcing the risk of other non-communicable diseases. Obesity is recognized by chronic low-grade systemic inflammation. New biomarkers for early detection of obesity risk are urgently required. The aim of this study was to identify the connection between pregestational BMI (pre-BMI) status and inflammatory biomarkers during third trimester of pregnancy and their association with intestinal microbiota composition. Fifty-four pregnant women were classified according to pre-pregnancy BMI as normoweight, overweight or obese. Weight gain, inflammatory biomarkers (hs_CRP, haptoglobin and suPAR) and microbiota composition were assessed during third trimester. A significant lower weight gain for obese mothers and a positive correlation between pre-BMI and inflammatory biomarkers was detected (Spearman's correlation). Haptoglobin levels were significantly higher in overweight and obese mothers. Higher Firmicutes levels and a higher ratio Firmicutes/Bacteroidetes were observed in the obese group and high hs_CRP and haptoglobin levels correlated with decreased microbiota diversity (Shannon index). Whereas haptoglobin and hs_CRP values were correlated with several microbiota components such as Ruminococcus gnavus and Faecalibacterium, and with specific phyla in the normoweight and overweight groups, no significant associations with microbiota were found for suPAR. In conclusion, haptoglobin and hs_CRP reflected pregestational BMI status and related microbiota components but haptoglobin was a better biomarker for microbiota associated to overweight. suPAR was associated with low grade of inflammation dependent on pre-pregnancy BMI, but it was not related to deviated microbiota profiles.