Prelab is a synthetic progesterone derivative that is used in the treatment of recurrent miscarriages (pregnancy loss) and premature labor. Prelab can be taken with or without food, but take it at the same time to get the most benefit. It should be taken as your doctor's advice. The dose and how often you take it depends on what you are taking it for. Your doctor will decide how much you need to improve your symptoms. Swallow the tablets whole with a drink of water. You should take this medicine for as long as it is prescribed for you. Do not miss even a single dose, if in any case you missed dose, take it as soon as you remember or better to skip the missed dose and continue with regular dosing. The most common side effects of this medicine include edema (selling), abdominal bloating, nausea, and vomiting. If these bother you, or appear serious, let your doctor know. There may be ways of reducing or preventing them. If medicine make you feel dizzy, better to avoid driving or attention seeking activities. Before taking this medicine, let your doctor know if you have ever had undiagnosed vaginal bleeding, or incomplete abortion or have heart disease or kidney problem. Your doctor should also know about all other medicines you are taking as many of these may make this medicine less effective or change the way it works.