Pregnant breasts grow too big may be physiological factors, need to pay attention to cleanliness and hygiene, anti-chafing care and wear more comfortable underwear. It may also be a pathological phenomenon, such as pituitary gland lesions, ovarian lesions, breast tumors, etc. Surgery, radiotherapy and other treatments should be chosen for the cause. 1. Physiological phenomenon: After pregnancy, women will secrete a large amount of estrogen and progesterone, which will stimulate the mammary glands to develop, which is a normal physiological phenomenon to prepare the body for lactation afterwards. Moreover, with the growth of pregnancy, the swelling and discomfort will be strengthened, so it is necessary to pay attention to cleanliness and hygiene, anti-chafing care as well as wearing more comfortable underwear. (1) Cleaning and hygiene: In the second trimester, it is recommended that you wipe your breasts with soapy water and a soft towel for 1-2 minutes every day, and then clean them with water. (2) Anti-chafing care: Use 25% alcohol wipes 1-2 times a day to prevent chafing. (3) Comfortable underwear: Choose suitable and comfortable underwear, as loose as possible, and do not wear overly tight tops. 2. Pathology: (1) Pituitary gland lesions: such as pituitary tumor, etc., should be examined by cranial magnetic resonance first, and after clarifying the lesions, surgical treatment, etc. should be carried out. (2) Breast tumors: such as breast cancer, etc., should be surgically removed immediately after clarification, and radiotherapy, endocrine therapy and other auxiliary treatments should be carried out as appropriate after surgery. Pregnant breasts grow too big may also be breast hyperplasia, trauma and other reasons, if you are worried, you can go to the hospital for examination, in order to clarify whether it is a pathological condition or not, pathological causes should be treated in accordance with medical advice.