Maternal physiological factors influencing labor length

描述（由申请人提供）：世界卫生组织建议，世界上没有任何地区的剖腹产率在10- 15%之间是合理的。2004年，美国的总税率为29.1%，初级税率为20.6%。随着这些比率的上升，母亲和新生儿面临的发病率和死亡率风险也在上升。难产是剖腹产的最大原因，约占所有无产妇女剖腹产的50%。众所周知，到目前为止，子宫力量的[1]异常是难产的最大原因，而[1]难产的分娩进展到阴道分娩时，更有可能增加分娩时间。这提示可能涉及子宫疲劳。本研究将探讨可能的因素：[1]通过增加子宫疲劳而增加产程长度；[2]表示能源供应不足；[3]提示发生了肌层细胞损伤。具体目的是确定产程长短与产妇的携氧能力之间的关系；[2]水化状态；[3]营养底物状态；子宫肌层细胞损伤。将研究足月（大于或等于37周-小于或等于42周）的低风险、未分娩妇女（n = 73）的方便样本。通过对子宫疲劳的影响来确定导致产程延长的事件/条件，可能会揭示导致难产的因素。结果可能为替代性劳动管理策略提供支持。

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.