Barto posted:

The reason for the decline in status is linked to changes in marriage customs.
During the Tang, the great houses still held prestige but sometimes little else. The prestige was enough and men would spend a huge amount of money to obtain marriage with the scioness of a great house. In contrast, they usually avoided marriages with Tang princesses because the princesses could do whatever drat thing they pleased including divorce, which wasn't pleasant to the Tang dynasty male psyche. In any case, the great houses power is based on their name prestige. The Tang emperors were actually steppes barbarians so they didn't like that and eventually forced a link between status in government and "nobility" and this was eventually tied to the exam system. This changed the way kinship relationships worked and by the Song dynasty something had changed. Men no longer paid money to a women's family, rather they expected a dowry. In effect, women had lost their leverage. The Tang had also seen the introduction of legal concubines for the "common middle class man" further weakening the status of women.
The status of concubines was in between a wife and a maid, but by the 17th century Qing the legal status between maid, concubine and wife had blurred significantly- which was a bit of a nadir for Chinese womenkind.
Anyho, it was all the fault of that damned test or so some theorize.