Antenatal betrothals meant that parents on both sides got their children engaged before were born. It was the ultimate embodiment of the parental authority. This kind of marriage had many disadvantages. Sima Guan (1019-1086), a scholar in the Song Dynasty, once analyzed it in his book “The Family Codes”, “By the time the betrothed came of age, one of them might have become a rescal, or become seriously ill, or utterly poor, or have gone into mourning, or gone to work in a far place, which led to numerous cases of abandonment and lawsuits.”
For the sake of the social stability, governments prohibited the practice of antenatal betrothals by law in the Yuan, Ming and Qing dynasties (the 13th century to the early 20th century), but were unable to eradicate it entirely. In many Chinese movies in which the stories happened in the feudal times, you may find this kind of thing.