The Governing Council of the UN Development Programme established World Population Day in 1989, inspired by the public interest sparked by the "Day of Five Billion" on 11 July 1987, when the world's population reached five billion. In December 1990, the UN General Assembly, through resolution 45/216, affirmed the day's continuation to raise awareness of population issues and their links to development and the environment. Each year the day highlights a different theme — reproductive health, family planning, gender equality, and women's rights to make decisions about their own bodies and reproductive lives — alongside challenges posed by rapid population growth in some regions and population ageing in others. Governments and international organizations mark the occasion with awareness campaigns, seminars, and policy discussions, while the UN Population Fund (UNFPA) uses the day to rally support for reproductive health programs and the empowerment of women and girls worldwide.