I definitely have to spit it out. If I even feel it going down my throat while I'm eating food, I have to spit that bite of food out. I have a friend who is the same weeks pregnant as I am and she spits even more than I do. We both have an excessive amount of regular saliva- that we can swallow. The excessive mucous we do not swallow and keep spit cups or tissues nearby for this reason. Acid reflux, aka heartburn, is also normal during pregnancy. The mucous and the acid refulx are both due to pregnancy hormones. I feel bad that you've had to go through your whole pregnancy with this problem. If I remember correctly, I went through it the whole time with my first pregnancy but stopped sometime along the way with my second pregnancy. Don't be alarmed, though, because the spitting will stop pretty much as soon as you give birth. You should feel almost immediate relief.  You've only got a few weeks to go, so stay positive :)