Effects of the sampling time on the vaginal microbiota in healthy pregnant women: a prospective observational study

The vaginal microbiota of pregnant women with normal pregnancy outcomes was not necessarily dominated by <i>Lactobacillus</i> spp. Further studies are required to define the vaginal microbiota in healthy pregnant women. When vaginal fluid samples were collected from the same pregnant women at wake-up and bedtime under the same conditions, the differences between wake-up and bedtime samples were greater for women with high diversity of the vaginal microbiota than for those with low diversity. However, these differences were not sufficiently large to exceed individual differences, and almost no change in the abundances of the dominant genera was observed. Since the relative abundance of <i>Streptococcus</i> spp<i>.</i>, a non-dominant species of the vaginal microbiota tends to change between wake-up and bedtime, it might be necessary to collect samples before bedtime to detect group B <i>Streptococci</i>.