Welcome to Healthcare magic. 1. 4 times negative and 5th time positive, never heard before. However in this case i would only confirm by an early scan ( ultrasound ) 2. See in this stage to abort, its through medication ( Non invasive ), but ic can t be made an habit, as it can cause irregular periods and long term complication. 3.Suggest a protection in future. Any thing to ask ? don t hesitate. Thank you.