Examination of clinical factors affecting intrauterine microbiota

Abstract

Purpose: Following reports of an increase in implantation and pregnancy continuation rates by a higher percentage of Lactobacillus in the intrauterine microbiota, it has received attention in infertility treatment. This study aimed to examine Japanese women for intrauterine microbiota. Methods: The clinical background factors in women that influence the abundance of Lactobacillus in the bacterial microbiota were examined. We included 147 patients (31 and 116 in the follicular and luteal phase, respectively), from June 2018 to June 2020, who underwent their first intrauterine microbiota test and had not used antibiotics for at least 4 weeks before the test. In the luteal phase, we compared the background factors of women in cases with 90% or more and less than 90% of Lactobacillus. Differences in the intrauterine microbiota were examined during the follicular and luteal phases. Results: The proportion of Lactobacillus tended to be low among women aged 36 years and older with a history of childbirth (P = 0.0631). Some bacteria were only detected during the follicular and luteal phases, and the bacterial microbiota may change during the menstrual cycle. Conclusion: Bacterial microbiota in the uterus may differ between the follicular and luteal phases. Furthermore, it was shown that the rate of Lactobacillus may be lower in women (older than 36 years) who had given birth, indicating that intrauterine microbiological testing may be considered for these women in clinical practice.

Keywords

• chronic endometritis
• implantation failure
• intrauterine microbiota
• lactobacillus
• menstrual cycle