When a baby's head is stuck in the birth canal for an extended period of time, it cuts off the blood supply to the woman's surrounding organs.

VOA: special.2010.08.09

but over an extended period of time.

而是持续一段时间的事情。

I'm ~ing 课堂 - SpeakingMax英语口语达人

"The committee continues to anticipate that the economic conditions -- including low rates of resource utilization, subdued inflation trends and stable inflation expectations -- are likely to warrant exceptionally low levels for the federal funds rate for an extended period."

VOA: special.2011.04.29