There can be many signs of pregnancy before missing of periods. But remember, these sings can also be due to many reasons and require differential diagnosis. Signs before missing periods can be tiredness, frequent urination, breast tenderness, food craving, increased basal body temperature, fatigue, nausea, implantation bleeding etc. Whenever you have few of these symptoms followed by missed periods then take pregnancy test and if the test is negative then visit a doctor for proper diagnosis and treatment.