Breast swelling and a little pain in the nipple may be pregnancy, or other lesions may cause such symptoms, this is due to breast swelling and a little pain in the nipple, in the breast lobular hyperplasia as well as breast fibroid patients, there are also such clinical manifestations. In addition, some women may experience such clinical symptoms due to increased levels of progesterone in their bodies prior to the onset of menstruation, so it is unreliable to rely on this one symptom to diagnose whether or not you are pregnant. If you find that your period is delayed and you suspect that you are pregnant, it is best to take a urine pregnancy test or go to the hospital for a blood test to check for chorionic gonadotropin in your body, both of which are more definitive ways to check for pregnancy.