There are hard lumps in the breast during breastfeeding, but they are not painful for the following reasons: 1. Milk stagnation: The main treatment is to unblock and massage. If there is enough milk or even a large amount and the baby can’t finish it, or if there are too thin milk ducts or poorly ventilated milk ducts, it is easy to cause milk accumulation and hard lumps. It is recommended to use a breast pump to suck out the remaining milk after each baby eats it. If you have hard lumps in your breasts, you can use warm towels to warm them up or massage them gently to relieve them.2. Mastitis: If the symptoms are severe, you need to go to the hospital for ultrasound to check the cause and rule out mastitis. Wear cotton, loose corsets, avoid wearing tight corsets, so as not to cause excessive squeezing of the breasts, resulting in blocked milk, and keep a happy mood also helps the hard lumps dissipate.