There has long been a son preference in China, leading to high rates of female infanticide, as well as a strong tradition of restricting the freedom of movement of women, particularly upper class women, manifested through the practice of foot binding.
The legal and social status of women has greatly improved in the 20th century, especially in the 1970s after the One-Child Polity and Reform and Opening-up Policy came out.
In comparison, there were less than 12,000 men registered in these types of marriages in the same year.
In 1950, polygamy was outlawed and it seemed, for a while, that extramarital affairs were unheard of.
Women in China are facing serious pressures to be married, by family and friends.
Further, when a husband dies the bride is seen as property of her spouse's family.
Article 8 of the 1980 Marriage Law states, "after a marriage has been registered, the woman may become a member of the man's family, or the man may become a member of the woman's family, according to the agreed wishes of the two parties." More recently, there has been a surge in Chinese-foreign marriages in mainland China, with data showing these types of marriages are more common in women than in men.
In 2010, there were almost 40,000 women registered in Chinese-foreign marriages in mainland China.
Today, women who discover their husband has a "second wife" are less tolerant and now have the ability to ask for a divorce.
Men tend to travel to mainland China for work and business.
 There are now lawyers who specialize in representing these "second wives" so they are not taken advantage of if the relationship ends badly.  This documentary takes a look at the rights of second wives and some of the issues they face.