Twenty-year-old women’s breast development is not good, may be too little estrogen secretion, malnutrition, breast binding, less exercise and other reasons. 1. Estrogen secretion is too little: some adolescent girls estrogen secretion is not enough, which will affect the growth and development of the mammary ducts, resulting in poor mammary gland development, you can eat estrogen-rich food. 2. Malnutrition: If you have the habit of dieting and picky eating, it will easily lead to malnutrition, which will make it difficult for your breasts to develop normally, so it is recommended that you have a balanced diet and don’t go overboard with the pursuit of slimming. 3. Bundle breasts: Adolescent women will use bras, if you choose a small underwear, bundle breasts serious, will cause breast underdevelopment, so you should choose the right underwear. 4. Less exercise: women who do not exercise regularly will also cause chest muscle dysplasia, to combine work and rest, appropriate exercise. Twenty-year-old women with poor breast development can actively seek medical attention and follow the doctor’s instructions for reasonable treatment.