Hello, Most miscarriages occur during the first 13 weeks of pregnancy. A woman who has had a previous miscarriage has a 25% chance of having another , Mild to severe back pain (often worse than normal menstrual cramps),Weight loss,White-pink mucus,True contractions (very painful happening every 5-20 minutes),Brown or bright red bleeding with or without cramps are warning signs .With the appearance of this symptoms you must consult your doctor.