During childbirth, larger babies have more difficulty passing through the birth canal.

在生产时，较大的婴儿通过产道是有更多的问题的。

To preserve the required strength, the birth canal must be comparatively narrow.

为了保持足够的支撑力量，女性的生殖道必须变得相对狭窄。

For example, the size of our heads is restricted by the size of our mothers' birth canals.

例如，我们的头部大小是有限的，因为母亲的产道的大小也是有限的。

In infants, this could happen when the baby is pulled out of the birth canal by the arm during delivery.

在婴儿中，如果分娩时是通过婴儿手臂将其拉出产道，也可能会出现这种状况。

Or, since the birth canal is the point of departure for human life, could it be a way of praising them?

或者，产道是人类生命的出发点，难道这是一种赞美他们的方式？

Halfway into the birth canal and Mel had second thoughts.

进入产道的一半时，梅尔又改变了想法。

You've got a chamber, which is the uterus and you've got a birth canal.

你有一个房间， 也就是子宫， 你有一个产道。

The obstetric dilemma goes like this: if our brains were any bigger at birth, they wouldn't fit out the birth canal.

产科难题是这样的：如果我们的大脑在出生时更大，那它们就不适合产道的尺寸。

Then at the end of it all, a big old baby goes through your birth canal.

然后在这一切结束时，一个大婴儿穿过你的产道。

Then, there’s giving birth, which involves forcing a 4-pound cub through an inch-wide, 23-inch-long birth canal, which is...not easy.

然后是分娩， 这包括迫使一只 4 磅重的幼崽通过一英寸宽、23 英寸长的产道， 这… … 并不容易。