First, ancient women were delicate.
We know that the status of ancient women was not high, and naturally their bodies were not well nourished during their growth. So generally speaking, most ancient women were not as healthy as women today. Poor health, insufficient natural milk. If you breastfeed yourself, your child won't starve to death. You need to find a wet nurse to supplement your child with enough milk!
In addition, many women are too weak to take care of a crying and noisy baby after giving birth. At this time, with the care of the wet nurse, women can get enough rest to recuperate themselves.
Second: the ancient class concept was too heavy.
In ancient times, we knew that we should say "scholar, agriculture, industry and commerce" to classify people. The concept of hierarchy has a long history. Everyone attaches great importance to the class status of individual families, and people are not as good as dogs. In ancient times, wet nurses were only enjoyed by upper-class people. As a big family, if you can afford a wet nurse, it will be considered as a symbol of status, indicating that the class is high, and this compulsion still needs to be installed!
Third: keep fit.
As we all know, there was no such thing as "family planning" in ancient times, and it was abnormal for a woman to have four or five children. Imagine that after giving birth to four or five children, you have to breastfeed yourself, and that figure has to be out of shape. And in a big house, three wives and four concubines are indispensable. When you are out of shape, I'm afraid men don't even want to see you. If you fall out of favor, the bitter days will come, and you may be bullied by other concubines or even die. Therefore, the wet nurse is not too important to her own woman!
But in any case, under this system, it did give birth to the profession of wet nurse. Many poor families did earn a lot of money by being wet nurses, and even entered a big family, soaring!