A bit of numbness in the breast during breastfeeding may be caused by physiological phenomena or pathological reasons (angina, mastitis, breast cancer, etc.). 1. Physiological phenomenon: lactation female lactogen level is high, easy to lead to the expansion of the milk ducts, there will be sensitive, numb feeling in the chest, belonging to the normal physiological phenomenon of lactation breast lactation. 2. Pathological causes. (1) angina: if overwork, emotional excitement, easy to lead to myocardial ischemia, resulting in angina attacks, accompanied by breast sensory abnormalities, breast lactation will appear chest numbness, need to be vigilant and timely to the hospital for examination. (2) Mastitis: due to the malformation of the milk ducts or nipple deformity can easily lead to the accumulation of milk, which can lead to the blockage of the milk ducts and the formation of mastitis, and there will be numbness in the chest, accompanied by tingling, etc. The symptoms of breast cancer are not only the symptoms of breast cancer, but also the symptoms of breast pain. (3) Breast cancer: the local nerve tissue of the breast is more, if the patient is not treated in time, it is easy to lead to nerve damage, and there is numbness in the breast during breastfeeding. The breast is a bit numb during breastfeeding, this situation should go to the hospital in time to find out the reason, for the cause of treatment.