The second-stage of labor is the most stressful part of childbirth process and the proper maternal position during this period is paramount for women's safe vaginal birth. Midwives play a pivotal role in managing maternal positions during the second-stage of labor. However, there is limited evidence to support an ideal maternal position during the second-stage of labor. Further, the difference between different maternal positions might not be apparent. This paper aims to review and compare the benefits and risks of common maternal positions during the second-stage of labor, thereby to provide midwives evidence-based practical guidelines.

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Background: Hypoxia is a risk factor for non-alcoholic fatty liver diseases, leading to permanent imbalance of liver lipid homeostasis and steatohepatitis. The current study examined the effect of HIF-2α, an oxygen-sensitive heterodimeric transcription factor, on hypoxia-induced dysregulation of lipid metabolism in HepG2 cells. Methods: Studies were conducted in C57BL/6 male mice and human HepG2 cells under hypoxic conditions, transfected with HIF-2α-targeted shRNA. The mRNA and protein expressions of key genes relevant to lipid metabolism were determined via RT-qPCR and western blot, respectively. Intracellular lipid accumulation was determined by Nile red, filipin staining and quantitative assay kits. Results: HIF-2α protein was quantified in both HepG2 cells and C57BL/6 mice under hypoxic conditions. Intracellular lipid accumulation and increased lipid levels induced by hypoxia were significantly reduced by silence of HIF-2α expression, associated with reversed expression of ABCA1 and ADRP, key genes in involved cholesterol excretion and fatty acid uptake respectively. However, HIF-2α had no effect on enzymatic activity and expression of key genes involved in fatty acid β-oxidation or cholesterol metabolism. Conclusion: Inhibition of HIF-2α protein reversed lipid metabolism dysregulation induced by acute hypoxia in HepG2 cells, which suggested that HIF-2α signaling may be relevant to oxygen-dependent lipid homeostasis in the liver.

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Aims To assess the effects of upright positions on maternal outcomes for women without epidural analgesia in comparison with recumbent positions during the second stage of labour. Background Upright positions have many physiological advantages. The underlying benefits and risks of upright positions during the second stage of labour have been reported in many studies but the results are divergent. Design A meta‐analysis of randomized controlled trials. Data sources The Cochrane Library, PubMed, Embase, CINAHL and ProQuest databases were systematically searched from inception to 17 June 2019. Review methods We conducted the quality appraisal using the Cochrane Collaboration's tool and performed meta‐analyses using the Review Manager 5.3 software. The primary outcomes were instrumental vaginal delivery and the duration of the second stage of labour. Results Overall, 12 studies including 4,314 women were included. Upright positions significantly decreased the rate of instrumental vaginal delivery (risk ratio [RR] = 0.74, 95% CI 0.59–0.93), shortened the active pushing phase (mean difference [MD] = −8.16 min, 95% CI −16.29 to −0.02), decreased the rate of severe perineal trauma (RR = 0.35, 95% CI 0.14–0.87) and episiotomy (RR = 0.52, 95% CI 0.29–0.92), but significantly increased the rate of second‐degree perineal trauma (RR = 1.45, 95% CI 1.10–1.90). However, there was no significant difference in the duration of the second stage of labour or postpartum haemorrhage. Conclusions Upright positions are beneficial for improving maternal outcomes. Several results should be considered with caution. Researchers need to clarify the definition of upright positions and conduct large, robust studies in the future to provide stronger evidence. Impact This meta‐analysis explores a crucial issue in intrapartum care and clarifies the benefits and possible risks of upright positions in the second stage of labour. Midwives and obstetricians are encouraged to apply upright positions depending on women's preferences and labour progress but should take measures to prevent perineal trauma.

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Given that the effects of ultrafine fractions (< 0.1 μm) on reproductive diseases are gaining attention, this study aimed to explore the influence of silica nanoparticle (SiNP)-induced female reproductive dysfunction. In this study, 80 female mice were randomly divided into four groups including a control group and three concentrations of SiNP groups (7, 21, 35 mg/kg). Mice were exposed to the vehicle control and silica nanoparticles by tracheal perfusion every 3 days a total of five times in 15 days. Then, half of the mice in each group were sacrificed on 15 and 30 days after the first dose, respectively. Our findings indicated that SiNPs can result in ovarian damage, cause an imbalance of sex hormones, increase the number of atretic and primary follicles, and induce oxidative stress and DNA strand breaks in ovary by day 15. The protein expressions of ATM, CHK-2, P53, E2F1, P73, BAX, Caspase-9, and Caspase-3 were significantly increased, while expressions of RAD51 were down-regulated after SiNP exposure by days 15. Estradiol increased, while progesterone increased in low dose and decreased in high dose after SiNP exposure by 15 days. However, these changes were recovered by 30 days. The results suggest that SiNPs can cause reversible damage to follicles in mice. SiNPs could primarily cause DNA damage and DNA damage response through oxidative stress, while DNA damage repair failure because of severe DNA damage activated the mitochondrial apoptosis pathway and therefore resulted in apoptosis of granulosa cell. In addition, the disorder of reproductive endocrine function caused by SiNPs could be another reason for SiNP-induced reproductive dysfunction in mice. These events in turn induce the follicles to undergo atresia.