There are a few possible reasons for this stop-n-go. As paediatrician Molly O'Shea , MD, explains, it could have to do with the fact that your period isn't entirely liquid, which can sometimes slow things down. "Sometimes if you have a chunk of tissue that blocks up the flow out the cervix, you can get a heavier flow again after it passes," she writes . It might also have to do with your changing hormone levels, Sandy Knauf, FNP, writes . In the beginning of your period, your oestrogen and progesterone levels stay steady and tend to produce a pretty continuous amount of bleeding. But that tapers off as your oestrogen level starts to rise again and your period starts to wrap up. These changes can definitely create a stop-and-start situation.