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

胎盘组织残留会阻碍子宫有效收缩，而导致宫缩乏力。

But if it does happen, the resulting uterine contractions and increased lubrication can help draw up and hold sperm in the uterus.

但是如果真发了，由此子宫收缩润滑增加有助于在子宫中吸收保持精子。

The amount of bleeding can vary, and it can be intermittent or continuous, sometimes increasing during labor because of uterine contractions and cervical dilation.

量不等，可能是间断或连，有时在时由于宫颈扩张，量会增多。

Power refers to forceful uterine contractions, passenger refers to the fetus, and passage refers to the route that the fetus has to travel through the bony pelvis.

力指有力子宫收缩，娩物指胎儿，道指胎儿穿过骨盆路径。

It can also occur when a woman is unable to empty her bladder, since a full bladder can push against the uterus and interfere with uterine contractions.

不仅如此，膀胱排空障碍也能引起后子宫收缩乏力，因为充盈膀胱将推挤子宫，进而阻碍子宫有效收缩。

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，一些科常用药物如麻醉药（特别是氟烷）、硫酸镁、硝苯地平特布他林等也会影响后子宫正常收缩，增加宫缩乏力风险。