Further Treatments: Steroids & Stopping Labour
Studies have looked at trying to stop labour when it starts after the waters have gone, but there is no real benefit in terms of significant prolongation of the pregnancy. Steroid injections are prescribed (usually in pregnancies before 34 weeks) to help mature the baby's lungs. They aren't the type of steroids that make you muscular, but they stimulate the babe's lungs to prepare for breathing air. Should you not go on to deliver, this doesn't do any harm, so there are really no draw backs to having them.
Sometimes drugs are used to stop labour to allow the steroid course to be completed; this normally takes about 24 to 36 hours. Also,labour may be stopped while mum is transferred to a hospital able to manage a premature infant.
From this link
http://www.womens-health.co.uk/prom.asp