'Hard' in the Bible

Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.

And they journeyed from Bethel; and there was but a little way to come to Ephrath: and Rachel travailed, and she had hard labour.

And it came to pass, when she was in hard labour, that the midwife said unto her, Fear not; thou shalt have this son also.