What does uterus mean in poetry?

First, in ancient poetry, although there are poems with the word "uterus", they basically have nothing to do with uterus, and most of them are two separate words. For example:

Zhang Ji wrote in the Tang Dynasty: "Luoyang City caught fire and soldiers burned my uterus." Here "the son of heaven" is a word, referring to the emperor. "Palace" means palace. In the Song Dynasty, Wu said, "Even if I have two or three friends, I will put my uterus back.". The word "Shizi" here refers to the disciple of Sakyamuni, that is, the disciple of Buddha. "Palace" means temple. Liu Song in the Ming Dynasty said, "Take off the white clouds and find the fairy uterus." Fairy Palace refers to the residence of immortals. There are many such things, such as Taiyi Palace, Yu Tai Palace and so on. Which ones are not "uterus". Secondly, in modern poetry, the uterus mostly represents images such as life, hope, rebirth and maternal elegance.