Nigeria is a state party of the Convention on the Elimination of All Forms of Discrimination Against Women It also has signed the Maputo Protocol, an international treaty on women's rights, and the African Union Women's Rights Framework. Discrimination based on sex is a significant human rights issue. Forced marriages are common. Child marriage remains common in Northern Nigeria; 39% of girls are married before age 15, although the Marriage Rights Act banning marriage of girls below 18 years old was introduced on a federal level in 2008. There is rampant polygamy in Northern Nigeria. Submission of the wife to her husband and domestic violence are common. Women have fewer land rights. Maternal mortality was at 814 per 100,000 live births in 2015. Female genital mutilation is common, although a ban was implemented in 2015. In Nigeria, at least half a million suffer from vaginal fistula, largely as a result of lack of medical care. Early marriages can result in the fistula.