Pregnancy 40 days suddenly chest soft not swelling pain may be physiological phenomenon, may also be due to the embryonic arrest and so on, need to be specifically analyzed. 1. physiological phenomenon: after pregnancy, with the body of estrogen, progesterone level of the sudden rise, may lead to the expansion of the chest capillaries, resulting in chest swelling, until the 40 days of pregnancy suddenly chest soft and soft not swelling, may be due to the breast to adapt to the role of estrogen and progesterone lead to. 2. Embryonic sterilizations: 40 days pregnant suddenly chest soft and not swelling pain, may also be due to the embryonic sterilizations caused by the decline in estrogen and progesterone levels, so that the breasts have lost the role of estrogen and progesterone due. The patient may also be accompanied by vaginal bleeding, abdominal pain and other abnormal symptoms. If you are pregnant for 40 days and suddenly your breasts are soft and not swollen, you need to consult a doctor in time, complete the relevant examinations to ascertain whether it is normal or not, and then carry out targeted treatment and therapy.