Effect of transvaginal Lactobacillus supplementation on reversing lower genital tract dysbiosis and improving perinatal outcomes in PCOS patients after IVF-FET: a study protocol for a multicenter randomized controlled trial.

Background: Significant lower genital tract (LGT) dysbiosis and an associated lower rate of clinical pregnancy after in vitro fertilization–frozen embryo transfer (IVF-FET) among polycystic ovary syndrome (PCOS) patients have been previously reported by our group. We aimed to assess whether transvaginal Lactobacillus supplementation can reverse LGT dysbiosis and further improve perinatal outcomes in PCOS patients after IVF-FET. Methods/design: This is a protocol for a multicenter, open-label, randomized controlled trial in China. Women diagnosed with PCOS who are undergoing IVF-FET treatment will be recruited. Allocation to the intervention/control arms at a ratio of 1:1 will be executed by an electronic randomization system. Participants in the intervention arm will receive the live Lactobacillus capsule vaginally for 10 consecutive days before embryo transfer, while those in the control arm will receive standard individualized care. The primary outcomes will be the clinical pregnancy rate, implantation rate, and live birth rate. 16S rRNA sequencing and liquid chromatography–mass spectrometry will be conducted to evaluate the LGT microbiome and systemic metabonomics before and after the intervention. A sample of 260 participants will provide 95% power to detect a 20% increase in the rate of clinical pregnancy (α = 0.025, one-tailed test, 15% dropout rate). A total of 300 participants will be recruited. Discussion: This is the first large and multicenter randomized controlled trial aimed at assessing the efficacy of transvaginal Lactobacillus supplementation on restoring the LGT microbiome and improving perinatal outcomes in PCOS patients after IVF-FET. This pragmatic trial is promising for increasing the rates of clinical pregnancy and live birth in PCOS patients after IVF-FET. Ethics and dissemination: Ethical review approval was obtained from the Medical Research Ethics Committees of the International Peace Maternity and Child Health Hospital of Shanghai Jiao Tong University (15 October 2020, GKLW 2020-29). To maximize dissemination, these findings will be reported in open access publications in journals with high impact, and oral and poster conference presentations will be performed. Trial registration: ChiCTR ChiCTR2000036460. Registered on 13 September 2020, https://www.chictr.org.cn/showproj.html?proj=59549. [ABSTRACT FROM AUTHOR]