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

胎盘组织残留会阻碍宫的有效收缩，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.

宫缩乏力还可以发由分娩程中产程延长引起的宫肌肉疲劳时。

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

，宫收缩乏力的患者，她们的宫肌层在产后能继续收缩；没有压力作用胎盘动脉，导致失血多。

Alright, as a quick recap, postpartum hemorrhage is the most common cause of maternal morbidity and mortality around the world, and the causes are the 4 T’s: Tone (atony), Trauma, Tissue, and Thrombus (coagulopathy).

好！快速回顾一下：产后出血是全世界孕产妇发病和死亡的最主要原因；其原因可归结为“4T”：宫缩乏力（Tone）、产道损伤（Trauma）、胎盘滞留（Tissue）与凝血功能障碍（Thrombus）。

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代指宫张力缺乏或宫乏力，也就是柔软的、海绵状的、水肿的宫，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。