sex worked both times for me, i had my two a week early from having sex, at least i think it was that and not just a fluke lol
i just found this on the net...
Love-making Sexual intercourse is thought to work in two ways. It may trigger the release of a hormone called oxytocin the 'contraction' hormone and this may increase the frequency of Braxton-Hicks, or practice, contractions. Semen also contains substances called prostaglandins. These can help to ripen, or soften, the neck of the womb (cervix) ready for it to dilate when labour contractions start.
If you think your waters may have broken, don't make love as this may increase the risk of infection, but do seek advice from your midwife or your local maternity unit.
Nipple stimulation This will release the hormone oxytocin and may help start labour. It's only likely to be successful if your cervix is 'ripe' and ready to dilate, otherwise it seems to help with the ripening process. There is no agreement on how much nipple stimulation you need, or how often, to stimulate contractions.
Walking This is also a common suggestion. The explanation appears to be that the pressure of your baby's head pressing down on the cervix from the inside stimulates the release of oxytocin, hopefully bringing on labour. If your baby has not 'dropped' or is still high in the pelvis, walking will also encourage your baby into a better position so that labour is more likely to start on its own.
Complementary therapies Some women find complementary therapies, such as acupuncture or reflexology, helpful for getting things moving. Always take advice from a qualified practitioner who is aware of your medical history and has experience of working with pregnant women.
You should ignore suggestions that you take laxatives, such as castor oil or enemas, which stimulate bowel action. These can lead to discomfort, sometimes pain and possibly complications, such as infections or dehydration.