Is this mucus plug ??

Been having contractions since 5am they were 10 min apart for 2.5 hours at first then went away for 6 hours and are coming back but are not consistent yet, they come every 5–20 mins rn. But i’ve been having brown discharge all day and then this just came out. I’m assuming it’s mucus plug?? Am i in labor ?? Due date was yesterday and was 3cm yesterday at dr appt