Investigation Into The Efficacy And Safety Of Sildenafil Versus Natural Progesterone For prevention Of Preterm Labour A randomized controlled study

This study is comparing two medications — Sildenafil (commonly known as Viagra, used here as a muscle relaxant) and natural progesterone — to find out which is safer and more effective at preventing premature labor in pregnant women who have had a previous preterm birth. Participants will start the medication between 18 and 24 weeks of pregnancy. You may be eligible if: - You are a pregnant woman between 18 and 40 years old - You are between 18 and 24 weeks pregnant - You have had at least one previous preterm birth (between 20 and 36 weeks plus 6 days) - You are not currently having symptoms of preterm labor You may NOT be eligible if: - You are carrying twins or more - Your membranes have already ruptured (waters broken) - You have vaginal bleeding - You have diabetes - You have a history of heart or cardiovascular disease - You have pre-eclampsia, placenta previa, or significant placenta problems - Your baby has a congenital abnormality - You have active liver disease, kidney problems, or a recent stroke or heart attack Talk to your doctor about whether this trial might be right for you.