I think for most, the worst of the afterpains occurs from about 24hrs to 72hrs...with lots of variation. I've heard women report afterpains for days longer, and it was normal for them--but that is more unusual. Mind you, the contractions that are shrinking the uterus do go on for weeks, it takes time for the uterus to shrink all the way down to normal again. It's just that after the 3rd-4th day, the pains most often subside--they are not as intense or as frequent. Some women don't notice them at all anymore, others notice but it's not so painful as it was at first. I would definitely be concerned about strong pains that persisted for several days--infection is one possible problem that could be going on.