Not sure about the pineapple thing...never heard that one.
Nipple stimulation causes your body to release oxytocin that causes uterine contractions. I work in the NICU and have had a couple of premature babies from Mom getting a head start on pumping while still pregnant. If you pump it will stimulate contractions.
Im guessing this means its safe to get out to the pump when your a lot closer to your due date then?
Yes, if you are within a week of your due date I say break out the breast pump or just get some oil and massage your nipples. The pump will have a stronger effect but massage can stimulate contractions as well. Evening primrose oil can soften the cervix. Black and Blue Cohosh can also bring on labor...just be cautious with using herbs to stimulate labor. I just have to say in my own opinion...Stay Away from Castor Oil....can cause baby to pass meconium in utero and that is bad news and can cause major respiratory distress. Besides anything that causes you to have stomach cramps in order to rev up contractions is miserable.