The reason why breasts do not swell when pregnant with a second child may be due to endocrine problems in women, because during normal pregnancy women’s breasts develop fully, and the ducts and alveoli of the mammary glands develop and prepare for the reserve of milk. If the breasts do not swell when pregnant with the second child, the most common clinical cause is caused by low endocrine function, due to the relative lack of estrogen, progesterone and prolactin content in the body, resulting in the failure of the normal development of the mammary gland cells, which may lead to the lack of swelling of the breasts, it is recommended that relevant tests can be performed. The performance of pregnancy will not be the same, some people have obvious chest swelling performance, and some may not, and it is also common in clinical practice. If the development of the fetus is normal there is no need to worry too much, keep your mood relaxed, do regular maternity checks, eat fresh vegetables, fruits and foods with high quality protein to promote breast development.