That's what dr-s told me first, keep my legs up and avoid stress. Huh, I got angry when I heard it, how can u avoid stress when you fear that little one! I suggest you to insist to check you via ultrasound and find it out what you really need. That's how they can lower your stress risk and I'm sure it can just help you!
In my case they prescribed me bedrest :S and medicines, but at least now at 23 weeks (contractions started more then one month ago) i really feel much better, and even can menage short walks without having pains after it!