Maternal physiological factors influencing labor length

描述（由申请人提供）：世界卫生组织建议，世界上没有一个地区的剖腹产率超过10- 15%。2004年，美国的总比率为29.1%，初级比率为20.6%。随着这些比率的上升，母亲和新生儿的发病率和死亡率风险也在上升。难产是剖腹产的最大贡献者，占未产妇剖腹产的近50%。众所周知，[1]到目前为止，子宫动力异常是难产的最大原因，[2]难产折磨的分娩进展到阴道分娩有更大的可能性增加产程长度。这表明可能与子宫疲劳有关。本研究将调查可能的因素：[1]通过增加子宫疲劳导致产程延长; [2]表明能量可用性不足; [3]表明子宫肌层细胞损伤已经发生。具体目标将确定产程长度与母体之间的关系：[1]携氧能力; [2]水合状态; [3]营养基质状态; [4]子宫肌层细胞损伤。将对足月（大于或等于37 -小于或等于42周）低风险、未经产分娩妇女（n = 73）的便利样本进行研究。通过对子宫疲劳的影响来识别有助于增加产程长度的事件/状况可能会揭示导致分娩难产的因素。研究结果可为替代劳动力管理策略提供支持。

DESCRIPTION (provided by applicant): The World Health Organization advises that no region in the world is justified in having a C-section rate >10- 15%. In 2004, the U.S. had a total rate of 29.1% and a primary rate of 20.6%. As these rates rise, so does the morbidity and mortality risk imposed on mothers and neonates. Dystocia is the greatest contributor to C- sections accounting for nearly 50% of all C-sections performed on nulliparous women. It is known that [1] abnormalities of uterine power are, by far, the greatest contributor to dystocia and [2] dystocia-afflicted labors that progress to a vaginal delivery have a much greater likelihood of increased labor lengths. This suggests uterine fatigue may be involved. This study will investigate factors that may: [1] contribute to increased labor length by increasing uterine fatigue; [2] indicate energy availability is inadequate; [3] indicate myometrial cell- damage has occurred. Specific aims will identify the relationships between labor length and maternal: [1] oxygen carrying capacity; [2] hydration status; [3] nutritive substrate status and; [4] myometrial cell-damage. A convenience sample of low-risk, nulliparous women in labor (n = 73) at term (greater than or equal to 37 - less than or equal to 42 wks) will be studied. Identifying events/conditions that contribute to increased labor length via effects on uterine fatigue may unveil factors contributing to labor dystocia. Results may offer support to alternative labor management strategies.