I don't think there's any out there I tried everything wih all my pregnancies but With my second pregnancy I was 38 weeks at that time my doc did membrane sweep & 6 hours later I was in labor... Good luck & congrats :)
Ive been doing A LOT of research cause I am going to start once I hit 37 weeks.. but the main things I have seen and read about and thats safe is.. walking, intercourse, eating eggplant parmesan, and stimulating your nipples start with one for 1min then on to the next and keep it up for 4 minutes. Then throughout the day.. if I find anything else I will definitely post to you some more but so far these are the main ones that are safe and supposedly does the trick. :))