First of all, there has always been a folk saying that prostitutes can't spend the New Year at their parents' home, because unmarried but pregnant prostitutes also belong to other people's families, which will offend their own geomantic omen, and at the same time offend their deceased ancestors, leading to the deterioration of their own geomantic omen, but this folk saying is incorrect.
Secondly, pregnant unmarried daughters who spend the New Year at their parents' home may be poor, which is not good for their families and will affect their fortune for one year. Therefore, a pregnant daughter can't go back to her parents' home for the New Year, especially her brother, which will ruin her family. Of course, this statement has no scientific basis, and people don't have to believe it.
In fact, pregnant unmarried girls can spend the New Year at their parents' home without affecting anyone in the family, but according to folk customs, pregnant unmarried girls also belong to other people's homes, which is equivalent to marrying others. It is better to spend the New Year at the man's house.