Maternal Metabolic Biomarkers are Associated with Obesity and Excess Gestational Weight Gain.

OBJECTIVE: The purpose of this study was to evaluate the independent contribution of maternal obesity and gestational weight gain (GWG) in excess of the Institute of Medicine's guidelines on levels of maternal serum inflammatory and metabolic measures. STUDY DESIGN: Banked maternal serum samples from 120 subjects with documented prepregnancy or first trimester body mass index (BMI) were utilized for analyte analyses. Validated, BMI-specific formulas were utilized to categorize GWG as either insufficient, at goal or excess based on the Institute of Medicine guidelines with gestational age adjustments. Serum was analyzed for known inflammatory or metabolic pathway intermediates using the Luminex xMap system with the MILLIPLEX Human Metabolic Hormone Magnetic Bead Panel. Measured analytes included interleukin-6, monocyte chemoattractant protein-1, and tumor necrosis factor-α and metabolic markers amylin, c-peptide, ghrelin, gastric inhibitory polypeptide, glucagon-like peptide-1, glucagon, insulin, leptin, pancreatic polypeptide, and peptide YY. Kruskal-Wallis ANOVA and Pearson's correlation coefficients were calculated for each marker. RESULTS: C-peptide, insulin, and leptin all varied significantly with both obesity and GWG while glucagon-like peptide-1 varied by BMI but not GWG. These analytes covaried with other metabolic analytes, but not with inflammatory analytes. CONCLUSION: Maternal metabolic biomarkers at delivery vary significantly with both obesity and GWG. Taken together, these findings suggest that GWG (with and without comorbid obesity) is an important mediator of measurable metabolites in pregnancy but is not necessarily accompanied by inflammatory measures in serum. These findings are consistent with GWG being an independent risk factor for metabolic disturbances during pregnancy.

The preterm placental microbiome varies in association with excess maternal gestational weight gain.

OBJECTIVE: Although a higher maternal body mass index is associated with preterm birth, it is unclear whether excess gestational weight gain (GWG) or obesity drives increased risk. We and others have shown that the placenta harbors microbiota, which is significantly different among preterm births. Our aim in this study was to investigate whether the preterm placental microbiome varies by virtue of obesity or alternately by excess GWG. STUDY DESIGN: Placentas (n=320) were collected from term and preterm pregnancies. Genomic DNA was extracted and subjected to metagenomic sequencing. Data were analyzed by clinical covariates that included the 2009 Institute of Medicine's GWG guideline and obesity. RESULTS: Analysis of 16S recombinant RNA-based metagenomics revealed no clustering of the microbiome by virtue of obesity (P=.161). Among women who spontaneously delivered preterm, there was again no clustering by obesity (P=.480), but there was significant clustering by excess GWG (P=.022). Moreover, among preterm births, detailed analysis identified microbial genera (family and genus level) and bacterial metabolic gene pathways that varied among pregnancies with excess GWG. Notably, excess GWG was associated with decreased microbial folate biosynthesis pathways and decreased butanoate metabolism (linear discriminate analysis, >3.0-fold). CONCLUSION: Although there were no significant alterations in the microbiome by virtue of obesity per se, excess GWG was associated with an altered microbiome and its metabolic profile among those women who experienced a preterm birth.