There’s not much predictability about the mucus plug. With my first pregnancy, I lost it all at once but didn’t go into labor until weeks later. With my second pregnancy, I didn’t lose any at all until my water broke—at which point it was tinged with blood. I dilated very fast after that and had bright red bleeding when I was closer to the end of dilation (don’t know how many cm because my only check was when I showed up at l&d with baby almost crowning).

It's your body getting ready for birth. Mention it to your doctor next appointment