A woman’s hard nipples during ovulation may be related to increased hormone levels in the body. A certain level of estrogen and progesterone can promote breast development, which can lead to increased nipple sensitivity and hard nipples. During this period, pay attention to good breast cleaning, avoid local extrusion and collision, otherwise it will lead to mastitis, and the situation of breast swelling and hard nipples can be relieved only after the onset of menstruation. In a menstrual cycle, not only the endometrium is affected by the hormones secreted by the ovaries, and changes in the menstrual, proliferative and secretory phases occur, but the breasts are also affected by the hormone levels in the body to change. If a woman’s nipples are distended and hard more obviously, sometimes she also needs to go to the hospital for breast ultrasound to avoid affecting the diagnosis and treatment of the disease.