Braxton Hicks vs. True Labor: What's the Difference?

Question
Hello, I am almost 35 weeks pregnant (will be tomorrow), this is my second pregnancy, but there are so many differences from my first that I just have to ask an expert about some recent experiences.  I have been experiencing what is believed to be false labor and just braxton hicks contractions.  The first major episode was a week ago; the contractions got fairly uncomfortable and even lasted for an hour at 2 minutes apart for almost a minute at a time, then they disapated and then completely went away.  My doctor said it was Braxton Hicks and that "if they were real contractions they'd stop me in my tracks" (even though my contractions didn't get uncomfortable for me at all with my first until I was in the hospital "in labor" for hours).  However, last night when I laid down in bed I experiences very comfortable and even painful contractions accompanied by lower back pain.  I had about 7 or 8 of them over the course of about 40 minutes but only 3 in a row were consistantly painful and evenly spaced by time (3 minutes apart for 15 seconds) and were so hard that I had to do the breathing to get through them.  Then they just went away completely.  I never experienced anything like that with my first and have heard stories of women having similar pains, they went away, and the women just wrote it off as Braxton Hicks, but they found out at their doctor's appointment the next day that they were already dilated and in labor. What does all this mean?  Should I go get checked to see if I'm dilating or just wait until they're more normal contractions even though my contractions were inconsistant throughout my first labor, so much so that after 8 hours the doctor wanted to use petosin?


Answer
The only difference between real labor pains and Braxton Hicks contractions, is that Braxton Hicks contractions, while they really hurt, will not cause dilatation of the cervix. When you start to have contractions at the level of your belly button that occur every 6 minutes (from the beginning of one contraction to the beginning of the next contraction) and each one lasts at least 45 seconds, and this continues for a full hour, then you are considered to be in labor. You still will have plenty of time to get to the doctor to be checked.