What does it mean to lose the mucus plug?

When you are pregnant you have a mucus plug that is there to stop bacteria entering your uterus and harming the baby. As you approach your due date and your cervix thins and dilates, the mucus plug can come out. It is just like a big bit of goo. Some women report seeing it fall into the toilet. Some women never notice it go. And sometimes it is still there when you go into labour. You can lose your plug up to two weeks before you go into labour, but it is one of the "signs" that your time is near.