Microplastics have been detected in various human organs, and studies on their impact on human health are ongoing. However, few studies have researched microplastics in the cervicovaginal area. In this study, we aimed to assess their presence in human cervicovaginal lavage fluid. This prospective study was conducted at a single tertiary medical center, enrolling 10 participants aged 27–49 years. Human cervicovaginal lavage fluid samples were collected from the patients by a single skilled obstetrician. Raman spectroscopy was used to analyze and characterize microplastic particles detected in the samples. Ninety-one microplastic particles were detected in 10 samples. More than 50% of the microplastic particles were identified in a single patient who regularly used menstrual cups. The mean number of microplastics was 9.10 ± 14.96 per 10 g sample. Most of the microplastics were <50 μm in size, and polypropylene and polystyrene were the most predominant types. Raman analysis detected microplastic particles in human cervicovaginal lavage fluids, suggesting that the human cervicovaginal area is exposed to microplastics. The number of detected particles varied significantly among individuals. This study highlights the need for further research on the effects of microplastics on the female reproductive system using cervicovaginal lavage fluid.

Objective: The purpose of this study was to determine the effect of vaginal progesterone for luteal phase support (LPS) on the clinical pregnancy rate (CPR) in natural frozen embryo transfer (FET) cycles via a meta-analysis.Methods: We performed a meta-analysis of randomized controlled trials (RCTs) and retrospective studies that met our selection criteria. Four online databases (PubMed, Embase, Medline, and the Cochrane Library) were searched between January 2017 and May 2017. Studies were selected according to predefined inclusion criteria and meta-analyzed using R software version 2.14.2. The main outcome measure was CPR.Results: A total of 18 studies were reviewed and assessed for eligibility. One RCT (n=435) and three retrospective studies (n=3,033) met the selection criteria. In a meta-analysis of the selected studies, we found no significant difference in the CPR (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.60–1.55) between the vaginal progesterone and control groups. An analysis of the two retrospective cohort studies that reported the live birth rate (LBR) following FET showed a significantly higher LBR in the vaginal progesterone group (OR, 1.72; 95% CI, 1.21–2.46). A subgroup meta-analysis of FET conducted 5 days after injection of human chorionic gonadotropin showed no significant differences between the two groups with regard to the CPR (OR, 1.18; 95% CI, 0.90–1.55) or miscarriage rate (OR, 0.73; 95% CI, 0.36–1.47).Conclusion: The results of this meta-analysis of the currently available literature suggest that LPS with vaginal progesterone in natural FET cycles does not improve the CPR.

Objective: We attempted to identify the optimal cutoff numbers of mature oocytes that would produce at least one or multiple top-quality (grade A) day-3 embryos in normal responders undergoing stimulated in vitro fertilization (IVF) cycles.Methods: We selected 210 fresh IVF cycles performed in 170 infertile women at a single center from January 2014 to November 2019. Four to 14 (total) oocytes were obtained in all cycles after conventional ovarian stimulation. A receiver operating characteristic curve analysis was performed to find the moderate and extreme cutoff numbers of mature oocytes that would produce ≥ 1, ≥ 2, ≥ 3, ≥ 4, and ≥ 5 top-quality embryos.Results: The cutoff number of mature oocytes was significantly correlated with the number of top-quality embryos (r = 0.467, p= 0.000). The moderate cutoff number of mature oocytes was ≥ 3, ≥ 5, ≥ 5, ≥ 6, and ≥ 6 for obtaining ≥ 1, ≥ 2, ≥ 3, ≥ 4, and ≥ 5 top-quality embryos, respectively. The extreme cutoff number of mature oocytes was ≥ 9, ≥ 9, ≥ 10, ≥ 10, and ≥ 11 for obtaining ≥ 1, ≥ 2, ≥ 3, ≥ 4, and ≥ 5 top-quality embryos, respectively.Conclusion: We present the optimal cutoff numbers of mature oocytes that would yield ≥ 1, ≥ 2, ≥ 3, ≥ 4, and ≥ 5 top-quality embryos with 95% specificity. Our findings could help infertility clinicians to set target mature oocyte numbers in women undergoing stimulated IVF cycles.

Objective: We investigated the impact of vitamin D3 (VD3) supplementation during mouse preantral follicle culture in vitro and the mRNA expression of 25-hydroxylase (CYP2R1), 1-alpha-hydroxylase (CYP27B1), and vitamin D receptor (VDR) in mouse ovarian follicles at different stages.Methods: Preantral follicles were retrieved from 39 BDF1 mice (7–8 weeks old) and then cultured in vitro for 12 days under VD3 supplementation (0, 25, and 50 pg/mL). Follicular development and the final oocyte acquisition were assessed. Preantral follicles were retrieved from 15 other BDF1 mice (7–8 weeks old) and cultured without VD3 supplementation. Three stages of mouse ovarian follicles were obtained (preantral, antral, and ruptured follicles). Total RNA was extracted from the pooled cells (from 20 follicles at each stage), and then reverse transcriptase-polymerase chain reaction was performed to identify mRNA for CYP2R1, CYP27B1, and VDR.Results: The survival of preantral follicles, rates of antrum formation and ruptured follicles (per initiated follicle) and the number of total or mature oocytes were all comparable among the three groups. Both CYP2R1 and CYP27B1 were expressed in antral and ruptured follicles, but not in preantral follicles. VDR was expressed in all three follicular stages.Conclusion: VD3 supplementation in vitro (25 or 50 pg/mL) did not enhance mouse follicular development or final oocyte acquisition. Follicular stage-specific expression of CYP2R1, CYP27B1, and VDR was observed.