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

Abstract Research Question What is the impact of a clinical pregnancy on the composition of the urinary microbiota? Design 85 women receiving an in-vitro fertilization (IVF), with or without intracytoplasmic sperm injection (IVF-ICSI) treatment were included in a prospective observational study performed in 2008. Approximately 14 weeks prior to the start of hormonal treatment and embryo transfer (ET), a midstream urine sample was obtained, followed by an additional sample 16 weeks after ET. The microbial composition was determined by PCR of the V1-V3 regions of the 16S rRNA bacterial gene. Pregnancy outcomes were collected both after the first IVF/IVF-ICSI cycle and subsequently one year later. Results A significant decrease in the abundance of Lactobacillus species as well as a significant increase in the abundance of Staphylococcus species was observed in women who became pregnant after IVF/IVF-ICSI treatment. In addition, based on the composition of the pretreatment microbiome it was possible to identify those women with a lower likelihood of achieving a clinical pregnancy after an IVF/IVF-ICSI treatment. The resulting prediction model was validated in another 27 women who did not become pregnant during the first cycle and received an additional IVF/IVF-ICSI cycle. The model predicted the women with no clinical pregnancy after IVF/IVF-ICSI treatment with a sensitivity of 0.42 and a specificity of 1.00. Conclusions Our data primarily showed that pregnancy results in significant changes in the abundance and diversity of urinary microbiota. Coincidentally, it was discovered that the urinary microbiome composition prior to IVF/IVF-ICSI treatment can potentially be used as predictor for clinical pregnancy outcome.