This systematic review and meta-analysis examined the relationship between menstrual cycle phases and the incidence of muscle injuries in female team sport athletes, following PRISMA 2020 and PERSiST guidelines. A comprehensive search was conducted in PubMed, Scopus, and SPORTDiscus from inception to mid-January 2024. Studies were included if they examined female team sport athletes of reproductive age with regular menstrual cycles and compared the occurrence of muscle injuries across at least two menstrual phases. Studies involving hormonal contraceptive use, medications affecting the menstrual cycle or musculoskeletal system, or menstrual dysfunction were excluded. Three studies met the inclusion criteria, involving 318 participants. Meta-analysis yielded a pooled Risk Ratio of 1.18 (95% CI: 0.75 to 1.86, p = 0.46) for injury risk between the luteal and follicular phases, suggesting no statistically significant association. However, the certainty of the cumulative evidence was rated as very low due to methodological limitations, including inconsistent phase classifications and reliance on imprecise methods for identifying menstrual phases. Consequently, no practical or clinical recommendations can be made at this time. Future research employing standardised, physiologically accurate methods for classifying and detecting menstrual cycle phases is necessary to better understand the potential links between hormonal fluctuations and injury risk. Supplementary Information: The online version contains supplementary material available at 10.1038/s41598-026-36763-0.
DOI 10.4324/9781351035620-4 10.4324/9781351035620-4
Cite this article
Guthardt, Y., Sargent, D., & Julian, R. (2026). The influence of the menstrual cycle on muscle injuries - a systematic review and meta-analysis. Scientific reports, 16(1), 3035. https://doi.org/10.1038/s41598-026-36763-0
Guthardt Y, Sargent D, Julian R. The influence of the menstrual cycle on muscle injuries - a systematic review and meta-analysis. Sci Rep. 2026;16(1):3035. doi:10.1038/s41598-026-36763-0
Guthardt, Yannik, et al. "The influence of the menstrual cycle on muscle injuries - a systematic review and meta-analysis." Scientific reports, vol. 16, no. 1, 2026, pp. 3035.
Iodine, an essential trace element, may play a role in reproductive health through its extrathyroidal actions. This study aimed to investigate the effects of iodine supplementation on oocyte apoptosis and proliferation in women with diminished ovarian reserve. A quasi-experimental study was conducted on ten women undergoing two cycles of ovarian stimulation. In the first cycle, they followed the standard protocol, while in the second, they received a daily 150 µg iodine supplement for two months. Urinary iodine levels, cumulus cell apoptosis and necrosis, and PCNA expression were evaluated before and after supplementation. We found that iodine supplementation significantly improved women's iodine status, increasing it from borderline sufficiency to optimal levels. This improvement was accompanied by a significant increase in the number of metaphase II oocytes. Following iodine supplementation, we observed a marked increase in cumulus cell viability and a reduction in both early and late apoptosis. Additionally, the expression of PCNA was upregulated, showing a positive association with the percentage of live cells and a reduction in total apoptosis. These findings suggest that iodine supplementation could be a promising therapeutic strategy for improving oocyte quality and enhancing fertility outcomes, particularly in women with diminished ovarian reserve.
AndrologyDNA FragmentationSperm DNA IntegrityOffspring Safety
Open Access
The role of sperm DNA fragmentation index (DFI) in investigating fertility, embryonic development, and pregnancy is of academic interest. However, there is ongoing controversy regarding the impact of DFI on pregnancy outcomes and the safety of offspring in the context of Assisted Reproductive Technology (ART). In this study, we conducted an analysis of clinical data obtained from 6330 patients who underwent in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) at the reproductive medical center of The First People's Hospital of Shangqiu and The Affiliated Hospital of Zhengzhou University. The patients was stratified IVF group and ICSI group, Within each group, patients were further classified into three subgroups. group A (< 15%) included 3123 patients, group B (15-30%) included 561 patients, and group C (≥ 30%) included 46 patients. group A (< 15%) included 1967 patients, group B (15-30%) included 462 patients, and group C (≥ 30%) included 171 patients. Data were collected and subjected to statistical analysis. There were no significant differences in the basic characteristics among the three groups, and the sperm DFI did not significantly affect the fertilization rates, pregnancy rates, stillbirth rates and the number of birth defects. However, the incidences of miscarriage rates in IVF/ICSI groups with DFI > 30% and DFI 15-30% were significantly higher than those in IVF/ICSI groups with DFI < 15%, and the miscarriage rates in ICSI group with DFI > 30% were significantly higher than DFI 15-30% group, the smooth fitting curve shows that there is a positive correlation between miscarriage rates and sperm DFI (OR 1.095; 95% CI 1.068-1.123; P < 0.001). The birth weight of infants in the IVF/ICSI groups with DFI > 30% and DFI 15-30% exhibited a statistically significant decrease compared to those in the IVF/ICSI groups with DFI < 15%. Furthermore, the birth weight of infants in the ICSI group with DFI > 30% was lower than that of the DFI 15-30% group. The smooth fitting curve analysis demonstrates a negative association between birth weight and sperm DFI (OR 0.913; 95% CI 0.890-0.937; P < 0.001). Sperm DFI has an impact on both miscarriage rates and birth weight in assisted reproductive technology. The smooth fitting curve analysis reveals a positive correlation between miscarriage rates and DFI, while a negative correlation is observed between birth weight and DFI.
Perimenopause/MenopauseReproductive Endocrinology
Open Access
This study tested progesterone for perimenopausal hot flush ± night sweat (vasomotor symptom, VMS) treatment. It was a double-blind, randomized trial of 300 mg oral micronized progesterone@bedtime versus placebo for 3-months (m) after a 1-m untreated baseline during 2012/1-2017/4. We randomized untreated, non-depressed, screenand baseline-eligible by VMS, perimenopausal women (with flow within 1-year), ages 35-58 (n = 189). Participants aged 50 (± SD = 4.6) were mostly White, educated, minimally overweight with 63% in late perimenopause; 93% participated remotely. The 1° outcome was 3rd-m VMS Score difference. Participants recorded VMS number and intensity (0-4 scale)/24 h on a VMS Calendar. Randomization required VMS (intensity 2-4/4) of sufficient frequency and/or ≥ 2/week night sweat awakenings. Baseline total VMS Score (SD) was 12.2 (11.3) without assignment difference. Third-m VMS Score did not differ by therapy (Rate Difference - 1.51). However, the 95% CI [- 3.97, 0.95] P = 0.222, did not exclude 3, a minimal clinically important difference. Women perceived progesterone caused decreased night sweats (P = 0.023) and improved sleep quality (P = 0.005); it decreased perimenopause-related life interference (P = 0.017) without increased depression. No serious adverse events occurred. Perimenopausal night sweats ± hot flushes are variable; this RCT was underpowered but could not exclude a minimal clinically important VMS benefit. Perceived night sweats and sleep quality significantly improved.
Preterm delivery of low-birth weight infants is considered a leading cause of morbidity and mortality among neonates. Various studies have reported a positive correlation between periodontal disease (PD) and premature birth (PB) and yet no population-based study has assessed the impact of PD severity and treatments on premature birth. This cohort study used Taiwan's national medical records (1999-2012, included 1,757,774 pregnant women) to investigate the association between PD severity and PB. Women with PD during the 2-year period prior for giving birth were more likely to have PB (11.38%) than those without PD (10.56%; p < 0.001). After variables adjustment, the advanced PD group had OR of 1.09 (95% CI 1.07-1.11) for PB, the mild PD group had OR of 1.05 (95% CI 1.04-1.06), while no-PD group had OR of 1. Increased PD severity was related to higher risk of PB. When stratified by age, the highest ORs for PB were those aged from 31 to 35 years in both mild PD group (OR = 1.09, 95% CI 1.07-1.11) and advanced PD group (OR = 1.13, 95% CI 1.09-1.17). Improving periodontal health before or during pregnancy may prevent or reduce the occurrence of adverse pregnancy outcomes and therefore maternal and perinatal morbidity and mortality.