I came across this.. quite interesting...
Orgasms to Induce Labor
You may have heard of couples who have engaged in sexual activity in order to naturally induce labor. Well, it has been shown that female orgasms can kick start labor contractions when they occur in the late stages of pregnancy. This is because of the fact that orgasm can cause your body to release oxytocin, a hormone which causes labor contractions. So, if you are past your due date and sick of waiting for baby, speak with your health care provider about engaging in sex to induce labor.
I have experienced B Hicks directly after and they last for a couple of hours... good luck
Frekkles 34 Weeks