"Three doors open at the same time" refers to blood vessels, abdominal muscles and pelvis. During pregnancy, these three parts will relax at the same time, just like three doors open together, which is called "three doors open at the same time". This situation usually occurs in the second and third trimester of pregnancy.

But please note that the phenomenon of "three doors open at the same time" does not apply to all pregnant women, and everyone's physical condition is different. If you have any questions or discomfort during pregnancy, it is recommended to consult a doctor in time.