Uterine Electrical Activity Before and After Progesterone Treatment for Preterm Labor

This study will examine the effects of various formulations of progesterone on uterine electromyographic (EMG) activity in pregnant patients in premature labor to determine if progesterone will suppress uterine electrical activity and which formulation may be best for inhibition of uterine activity. Patients will be monitored prior to treatment and following treatment (every 2 to 4 hours) with one of three different formulations of progesterone for up to two days. Patients will continue to be observed until they deliver. Comparisons will be for uterine EMG activity from before treatment to that following treatments at 2, 4, 8, 12 24 and 48 hours and times of delivery after treatments (hours or days following treatments). Comparisons between mean values for EMG activity between the various treatments at the various times will also be made.