This in turn prevents effective uterine contractions, and leads to uterine atony.

胎盘组织残留会阻碍子宫的有效收缩，而导致宫缩乏力。

Uterine atony can also occur when the uterine muscles fatigue during the delivery process because of prolonged labor.

宫缩乏力还可以发生于由分娩过程中产程延长引起的子宫肌肉疲劳时。

With uterine atony, though, the uterus fails to contract after birth, and those placental arteries don't clamp down, leading to excessive bleeding.

不过，对于子宫收缩乏力的患者，她们的子宫肌层在产后不能继续收缩；没有压力作用于胎盘动脉，导致失血过多。

Uterine atony can be treated by fundal massage, massaging the fundus – the upper section of the uterus which is typically near the umbilicus right after birth.

宫缩乏力可以通过宫底按摩进行治疗，也就是按摩子宫的底部，即子宫的上半部分；该部分将在分娩后下降到脐水平附近。

Finally, some commonly used obstetric medications such as anesthetics (especially halothane), magnesium sulfate, nifedipine, and terbutaline can all interfere with uterine contractions and increase the risk of uterine atony.

此外，一些产科常用药物如麻醉药（特别是氟烷）、硫酸镁、硝苯地平和特布他林等也会影响产后子宫的正常收缩，增加宫缩乏力的风险。

Tone refers to a lack of uterine tone or uterine atony – basically a soft, spongy, boggy uterus, and this is the main cause of postpartum hemorrhage, generally resulting in a slow and steady loss of blood.

Tone代指子宫张力缺乏或子宫乏力，也就是柔软的、海绵状的、水肿的子宫，这是产后出血的最主要原因，一般引起缓慢持续的血液丢失。