My high risk doctor told me that
during my next
pregnancy, he will have me take progesterone (in the form of vaginal suppositories, but some women get it as a shot) from weeks 15-36.... This is proven to be successful by reducing the chances of preterm labor by up to 40%...... if you have an irritable uterus, which is what I have too, they could help you!!
Also, new research is being conducted on the benefits of Omega-3 supplements to reduce the chances of preterm labor.