I took mine out around 20 weeks, I think. It was starting to be a tight fit - the ring stood straight out and I felt like I was bumping it on things. I know my friend kept hers in longer. My only 2 stretch marks so far (at 34 weeks) are 2 tiny ones right above and below the pierce mark. They're cute. I would think with a bar, esp a flexible one (is it long?), you could last a lot longer, maybe the whole time.