how do you know if you're at risk for preterm labor?

okay, i'm 24 weeks now, and lately i've been having an increase in discharge, especially after i pee... and, i read somewhere that you should be kinda worried if you have 4 or more BH contractions in an hour, well so far, I had one at 12, on at 12:20, and what seemed like a real small one at 12:30... and the hour's not up yet.. so what are your thoughts? should i be worried, and should i call my doctor? and also what would be the point of calling him, is there any way they can tell something is wrong or that there is a potential risk for preterm labor? i know you can't see these things coming, so i don't really know what to do or if i should be worried.. opinions please?

[adawning4]

With my first baby my doctor told me that if I thought I was in labor that I should take a warm bath and lay on my side for a little while and relax try to clear your head and think of nothing.... If the contractions continue then you should time them if they are about 5 minutes apart then call your doc. or go to the hospital.. I dont think there is no real way of know if its your first and your cervix is still closed.... let us know ok!

[KStarr07]

well i don't think i'm going into labor now, i just read that somewhere on a pregnancy site, things to look out for concerning preterm labor.. worried me. but i will sure keep an eye on it.... thanks.