Caulphyllium is a homeopathic remedy. My first MW (way back when!) recommended Caulphyllium 30, and start to take it at week 38. DS1 did come on time BTW!
Can't remember if I took it last time, but I still have the same bottle in the cupboard!
According to the blurb I got with my new birthing kit, its to keep contractions going if they slow down.