Mucus plug na po ba ito?

Ay mama, ang mucus plug talaga ay parang thick, jelly-like discharge (pwedeng may slight blood tinge), kaya kung yan ang nakita mo, that's a good sign na approaching na ang labor! But honestly, with the lower back and belly pain you're describing, I'd really suggest calling your OB or heading to the hospital para ma-check properly, hindi lang sila makikita ng eye lang if you're already in active labor or if something else is going on, and at 39 weeks and 3 days, you're definitely ready na. A few of my mum friends said na parang excited lang sila na gawin ng doctor ang check-up kasi at least they'll know kung close na talaga, so don't hesitate to go in and get peace of mind, sis!