Hi mama! Honestly, at 39 weeks, it's so normal for the belly to drop lower, that's actually your baby's way of getting ready to come out na! A few of us moms noticed our bellies looked different in those last few days, and our OB said it just means baby is engaging. But if you're worried or if it happened suddenly, better to check with your doctor right away para peace of mind mo, especially since first time mo pa lang, they can do a quick check and confirm everything is progressing well. Exciting times! You're so close na!