Maternal Gut Microbiome Biodiversity in Pregnancy

Objective To measure maternal gut microbiome biodiversity in pregnancy. Materials and Methods In phase 1, maternal fecal samples were collected by rectal swab in 20 healthy pregnant women (14-28 weeks gestation) to measure bacterial abundance. In phase 2, fecal samples were collected from 31 women at enrollment (<20 weeks gestation, baseline) and at 36 to 39 weeks of gestation (follow-up). We assessed cluster analysis to assess bacterial community profiles at the phylum level longitudinally through pregnancy. DNA was extracted from swabs, followed by PCR of the bacterial 16s rRNA gene and multiplex high-throughput sequencing (Ion Torrent). Results In phase 1, 16 of 20 samples yielded usable data. White women ( n =10) had greater abundance of Firmicutes (230.15 vs. 16%+/- 0.75, p =0.007) and Bacteroidetes (24 +/- 0.14 vs. 19%+/- 0.68, p =0.015) compared with non-White women ( n =6). In the 11 paired specimens, Bacteroidetes increased in abundance from baseline to follow-up. Compared with women who gained weight below the median gestational weight gain (GWG, <15.4 kg), those who gained above the median GWG had increased abundance of Bacteroidetes ( p =0.02) and other phyla ( p =0.04). Conclusion Maternal microbiome biodiversity changes as pregnancy progresses and correlates with GWG.