As space missions extend in duration, the impact of spaceflight on human reproduction poses serious biomedical challenges. The reproductive system is susceptible to microgravity, ionizing radiation, and circadian disruption. This review summarizes current evidence on how space environments affect reproductive function, focusing on gametogenesis, hormonal regulation, pregnancy, and embryonic development. We reviewed data from rodent models, parabolic flight experiments, and space-exposed cellular systems to assess the effect of space-relevant stressors on reproductive health. Findings show that microgravity impairs sperm motility and hormonal balance, while radiation increases DNA fragmentation and induces heritable epigenetic changes. Female reproductive health is similarly affected, with radiation accelerating follicular loss and hormonal disruption impairing ovulation. Early pregnancy stages, including implantation and placental development, are especially vulnerable to space conditions. Rodent studies indicate that while basic fertility may persist, the long-term effect on offspring health and multi-generational outcomes remains unclear. These findings highlight the need for targeted countermeasures and continued research to ensure reproductive success in future space missions.

The purpose of this study was to provide basic data for evaluating the reproductive health of bivalves using intersexuality. We analyzed purplish bifurcate mussel Mytilisepta virgata (n = 67, shell height 37.1±8.3 mm), Manila clam Ruditapes philippinarum (n = 288, shell length 28.6±4.2 mm) collected from coastal water near Yeosu, Korea. The sex ratio (female:male) of M. virgata and R. philippinarum were 1:1.5 and 1:0.8, respectively, and showed differences depending on the collection area. The total intersexuality of M. virgata was 20.9%. The intersexuality in female (33.3%) was higher than in male (12.5%), and the regional intersexuality was 72.7% in Sogyeongdo, 20.0% in Oesamdo and 5.6% in Jungsamdo with the highest in Sogyeongdo. The total intersexuality of R. philippinarum was 11.8%. The intersexuality in female (17.5%) was higher than in male (4.7%), and regional intersexuality was 20.0% in Neungchodo, 13.0% in Dokdo, 2.8% in Samdo, 5.9% in Orando, 19.6% in Oesamdo with the highest in Neungchodo. The incidence of intersexuality according to distance from cities and ports each sampling area showed no clear tendency. Intersex specimens were showed histological structure changes of digestive gland, such as digestive tubule disruption and necrosis of epithelial cells, accumulation of eosinophilic granules in lumen of tubule, necrosis of connective tissue. These results suggest that not only the histological structure of the digestive gland but also intersexuality should be used as important biomarker for toxicity assessment of pollutants.

The impact of heat stress (HS) on reproductive performance and its problems in cows remains to be investigated in Bangladesh. The study was, therefore, aimed to evaluate the effect of HS on fertility and reproductive health problems of dairy cows in a selected area of Bangladesh. A total of 1,095 cows from 500 farms were included in this study. The climate-related data were recorded daily basis for every month in a year and temperature-humidity index (THI) values were calculated to determine the level of HS. Concurrently, data on fertility parameters [number of services per conception (NSC), conception rate (CR) and calving to the first service interval (CFSI)], and reproductive problems were collected through a pre-defined questionnaire. The results show that crossbred [Native x Holstein-Friesian, (HF)] cows were more vulnerable (p < 0.05) to a magnitude of HS effects considering physiological parameters of cows [age, body condition score (BCS), parity and milk yield]. Regarding fertility, HS had no effect on NSC, CR and CFSI in both native and crossbred cows (p > 0.05). The findings on the reproductive problems indicate that HS had significant influence on the prevalence of anestrus (χ2 = 21.814, p < 0.05) and retained placenta (χ2 = 24.632, p < 0.05) in cows. Of note, the prevalence of repeat breeding syndrome was 2.5 folds higher in stress condition than in no stress condition. Abortion and dystocia were not influenced by HS. In conclusion, HS does not influence the fertility parameters of cows studied; however, anestrus and retained placenta are likely to occur under HS conditions in cows.

This study was carried out to investigate the reproduction efficiency and disease of Holstein heifer grazed on mixed pasture desighed with association of tall fescue and white clover cultivar (3 treatments = TI : Tall fescue Fawn + White clover Regal + Or