(HealthDay News) – Gut microbiota undergo remodeling over the course of pregnancy, with an increase in between-subject diversity and in Proteobacteria and Actinobacteria from the first to the third trimester.

Noting that gut microbiota can cause symptoms of metabolic syndrome, which are similar to the immune and metabolic changes that occur in normal pregnancy, Omry Koren, PhD, from Cornell University in Ithaca, NY, and colleagues examined the role of gut microbiota in normal pregnancy. Fecal bacteria from 91 pregnant women with varying pre-pregnancy body mass index and gestational diabetes status, and from their infants, were characterized.

The researchers found that infant microbiota was unaffected by the mother’s health, and the similarity between infant-mother microbiota increased with the child’s age. There was a notable change in the microbiota from the first to third trimester, with an increase in the diversity between mothers, an increase in Proteobacteria and Actinobacteria, and a decrease in within-subject diversity. Although microbiome gene repertoires were consistent between the trimesters, the strongest signs of inflammation and energy loss were seen in stool samples from the third trimester. Compared with microbiota from the first trimester, microbiota from the third trimester induced greater adiposity and insulin insensitivity when transferred to germ-free mice.

“Our findings indicate that host-microbial interactions that impact host metabolism can occur and may be beneficial in pregnancy,” the authors conclude.

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