Uy mama, congrats sa almost 39 weeks na! Mucus plug talaga yan most likely, lalo na at sobrang close mo na sa due date, kaya normal lang yan at sign na body mo ay nag-prepare na for labor. Pero if may bleeding pa or intense cramping along with it, best to call your OB right away para peace of mind mo, okay? Isa lang yan sa maraming signs bago magstart ang labor so just monitor mo, stay hydrated, at enjoy na ang last few days ng pregnancy mo!