Dynamics of the urinary microbiome in pregnancy and the coincidental predictive value of the microbiota for IVF/IVF–ICSI outcome

What is the impact of clinical pregnancy on the composition of the urinary microbiota? Eighty-five women receiving IVF, without or with intracytoplasmic sperm injection (ICSI) treatment were enrolled in a prospective observational study performed in 2008. Approximately 14 weeks before the start of hormonal treatment and embryo transfer, a midstream urine sample was obtained, followed by an additional sample 16 weeks after embryo transfer. The microbial composition was determined by polymerase chain reaction of the V1–V3 regions of the 16S rRNA bacterial gene. Clinical pregnancy data were collected after the first IVF/IVF–ICSI cycle and 1 year later. A significant decrease in the abundance of Lactobacillus species as well as a significant increase in that of Staphylococcus species was observed in women who became pregnant after IVF/IVF–ICSI treatment (both P