Reproductive Medicine

Background/Objectives: Infertility is a major public health concern, affecting one in six individuals worldwide and nearly one-quarter of couples in France. While a male, female, or combined factor can be identified in approximately 75% of cases, infertility remains unexplained in 10–25%. Genital tract infections account for roughly 15% of male infertility cases and are often asymptomatic, being detected incidentally during routine evaluation prior to assisted reproductive technology (ART). Emerging evidence suggests that the seminal microbiota may contribute to sperm quality and male reproductive health. This systematic review aims to evaluate whether specific microbial profiles are associated with alterations in semen parameters. Methods: A comprehensive literature search was conducted in PubMed and ScienceDirect, yielding 165 and 1418 records, respectively. In the end, 20 articles were included in this systematic review. Results: Men with normal semen parameters commonly exhibited a higher abundance of Lactobacillus and Bifidobacterium, whereas Prevotella was more frequently observed in individuals with impaired semen quality. Several taxa—such as Gardnerella, Corynebacterium, and Staphylococcus spp.—were detected in both normal and altered semen profiles, suggesting that their impact on sperm quality may depend on reaching a pathogenic threshold. Conclusions: Current evidence supports an association between seminal microbiota composition and sperm quality. However, the heterogeneity of available studies and the lack of standardized methodologies limit the ability to draw firm conclusions. Further well-designed studies are required to clarify causal relationships and to determine the clinical relevance of seminal microbiota assessment in male infertility.

Background/Objectives: Dynein axonemal heavy chain (DNAH) genes, including DNAH6, are implicated in male infertility, particularly multiple morphological abnormalities of the spermatozoa flagellum (MMAF). However, an underlying mechanism is unclear. Methods: This in silico study analyzed 19 previously reported DNAH6 mutations to elucidate their effects on the structural, mechanical, and microstructural aspects and axonemal assembly of flagellum and how these changes impact reproductive health, correlating with pathogenicity scores, ATP binding capacity, and protein interactions. Results: DNAH mutations were associated with CDGP (52.63%), male infertility (36.84%), and primary ovarian insufficiency (10.53%). MMAF-linked mutations exhibited higher SNAP2 scores (57.25 ± 5.68 vs. −32.58 ± 44.85, p = 0.002), reduced ATP binding affinity (−6.27 ± 4.20 vs. −8.92 ± 0.23 kcal/mol, p = 0.05), and smaller catalytic cavity size (17,646 ± 13,005 vs. 27190 ± 3485 ų, p = 0.04). These mutations showed reduced DNAH6-CLIP4 binding affinity (−303.90 ± 5.23 vs. −313.60 ± 4.28 kcal/mol, p = 0.002). Literature-based semen analysis revealed correlations between Phred scores and absent flagella (r = 0.952, p = 0.012) and inverse correlations between ATP binding capacity and absent flagella (r = −0.902, p = 0.036) or irregular width (r = −0.949, p = 0.014). A mathematical model of ATP binding kinetics predicted reduced flagellar motility in MMAF mutants due to impaired dynein function. Ultrastructural analyses indicated that high pathogenicity scores and reduced ATP binding correlate with absent inner dynein arms and radial spokes, while impaired DNAH6-CLIP4 interactions disrupt axonemal assembly. Conclusions: In silico analyses, integrated with microstructural, axonemal, and mathematical modeling data, demonstrate that DNAH6 mutations cause MMAF by impairing ATP binding, protein interactions, and axonemal assembly, leading to severe flagellar dysfunction and thereby negatively affecting reproductive health.

Background: Following gonadotropin-releasing hormone (GnRH) agonist trigger and “freeze all” in order to prevent ovarian hyper-stimulation syndrome (OHSS), patients are usually anxious to continue immediately with a frozen embryo transfer (FET). Currently, the preferred FET protocol in based on natural or induced ovulation. Objectives: Do ovarian stimulation and GnRH-a, used to trigger final oocyte maturation, affect the reproductive axis in the next natural cycle? Design: An observational case series of 100 subsequent in vitro fertilization (IVF) patients to whom GnRH-a (Triptorelin 0.2 mg) was given for final oocyte maturation in the context of ovarian hyper-stimulation syndrome prevention, followed by embryos “freeze all”. Methods: In the next natural cycle, patients were followed to detect a dominant follicle (≥17 mm), at which time ovulation was triggered with human chorionic gonadotropin (hCG, 250 µg), and FET was scheduled according to embryo’s age on freezing day. Results: Whereas natural ovulation according to pre-IVF treatment was predicted to be on cycle day 14, the actual hCG-scheduled ovulation in our patients was on day 21. In eight patients, follicular activity was not detected after 15–28 days; therefore, the natural cycle frozen embryo transfer approach was abandoned. Conclusions: Ovarian stimulation and GnRH-a used to trigger final oocyte maturation in IVF patients inhibits the reproductive axis for days. Therefore, natural ovulation in the subsequent cycle may be deferred for about one week relative to the patient’s pre-IVF menstrual cycle pattern. This may help schedule clinic visits to optimize monitoring efficiency.