Understanding Contractions in Late Pregnancy: 35-36 Weeks

Question
I am 26 years old and this is my first full pregnancy.  (two early miscarriages)  I am 35 almost 36 weeks pregnant, and beginning last night I began having contractions every 45 min to hour and a half.  Today was my last day at work, and I have been rather active.  Is this just a normal way for my body to prepare itself for the real thing, or is this just a really slow version of the real thing?

Answer
At this stage of pregnancy, you will start to get irregular contractions. They may start in your back or lower abdomen and will, eventually, localize to your belly button. When you get contractions at the level of your belly button that come every 3 minutes (from the beginning of one to the begnning of the next one) and each contraction remains hard for a full minute, and this continues for a full hour, we consider you to be in labor. This will usually start at around 38-40 weeks gestation. Now, you are having Braxton-Hicks contractins. They are not regular, are not at your belly button, and do not last for a full minute. Be patient and don't worry.