Millions of people around the world planned to demonstrate, attend conferences and enjoy artistic events Wednesday to mark International Women’s Day, an annual observance established to recognize women and to demand equality for half of the planet’s population.

While activists in some nations noted advances, repression in countries such as Afghanistan and Iran, and the large numbers of women and girls who experience sexual assaults and domestic violence worldwide highlighted the ongoing struggle to secure women’s rights.

United Nations Secretary-General Antonio Guterres noted this week that women’s rights were “abused, threatened and violated” around the world and gender equality won’t be achieved for 300 years given the current pace of change.

Progress won over decades is vanishing because “the patriarchy is fighting back,” Guterres said.

The United Nations recognized International Women’s Day in 1977, but the occasion has its roots in labor movements of the early 20th century. The day is commemorated in different ways and to varying degrees in different countries.

Women gathered in Pakistan’s major cities to march amid tight security. Organizers said the demonstrations were aimed at seeking rights guaranteed by the constitution. Some conservative groups last year threatened to stop similar marches by force.

Women’s rights activists in Japan held a small rally to renew their demand for the government to allow married couples to keep using different surnames. Under the 1898 civil code, a couple must adopt “the surname of the husband or wife” at the time of marriage.