At first, it refers to marriage between men and women or intermarriage between two families. Today, many women are instructed to be pregnant. Nowadays, it is mostly sexual intercourse between men and women, or men and women (mostly unmarried men and women) are pregnant because of infidelity.
The origin of the idiom "hidden in the womb": The Love Song of Cangyang Jiacuo is full of melancholy and spring breeze, stealing rain to plant evil roots. You can't hide before you fight for teaching, but you have a hidden heart knot. Pearl in the dark, Pearl in the dark Although these two idioms look very similar, their meanings are quite different. Concealed pregnancy is a derogatory term, which refers to the secret development of bad forces. Playing the lute to a cow means that good things fall into the wrong hands.
Source: Cangyang Jiacuo Love Song is a gloomy spring breeze in Yumen, which is rooted in stealing clouds and rain. You can't hide it until you argue, but you're pregnant. Word analysis: pearl embryo, undivided pearl in mussel. Dark, dark, unknown. "knot" refers to the ambiguous relationship between men and women or the pregnancy of men and women (mostly unmarried men and women) due to derailment.