The United Kingdom government of David Cameron and the Bill and Melinda Gates Foundation recently announced plans for a summit in London in July to raise funds for voluntary family planning so that everyone who wants it has access to the means to exercise this human right. UNFPA, the United Nations Population Fund, fully supports and is a partner in this historic initiative on an often-overlooked human right.

Since the late 1960s, the international community has proclaimed a person's right to family planning, that is the right to decide whether, when and how many times to have children, as well as to the means to exercise this human right. Those means include access to reproductive health care, including contraceptives, information, supplies and services. The right of individuals to determine freely the size of their families was emphasized and expanded by the 1994 International Conference on Population and Development, in Cairo. The Conference also put women at the very heart of population programs.

Yet, in the developing world, an estimated 215 million women who want to delay or avoid their next pregnancy cannot exercise this right as they lack modern contraceptives, resulting in unintended pregnancies, unsafe abortions and more than 100,000 maternal deaths. This is what the family planning summit in July will tackle.

There are many reasons why many women do not or cannot take advantage of family planning. Sometimes, there are obstacles related to weak transportation systems that hamper delivery of contraceptives to women in rural or remote areas. Such obstacles could also be cultural or social. Other times, misinformation about use and safety discourages women from seeking family planning.

In many places, family planning is provided by workers who lack the skills or sensitivity to respectfully, reliably and confidentially dispense advice, information and the full range of contraceptives.

Women often fear punishment, including violence by their partners or families, or stigma by the community, if they try to use contraception. Many do not have money to pay for services or transportation, or cannot take time away from their families, work or school to take advantage of services, even when they are available.

Modern contraceptive use among adolescents is generally low, and decreases with economic status. Fewer than 5 percent of the poorest young use modern ones. In too many cases, adolescents have no access to accurate information about contraceptives and their side effects. Among women who are married or in partnerships, unmet need for contraception is highest among those aged 15 to 24.

Providing for the unmet need for family planning requires not only tearing down the barriers that women and adolescents face in their homes and communities, but also expanding the availability of quality information, supplies and services. The Guttmacher Institute and UNFPA estimate that meeting the unmet need for modern family planning methods in developing countries would cost about $6.7 billion annually. With $3.1 billion of this total now being invested, we have a shortfall of $3.6 billion.

But ultimately and, most importantly, access to family planning is a human right. Governments that have ratified international human rights agreements, such as the Convention on the Elimination of All Forms of Discrimination Against Women, have an obligation to honor their commitments and protect human rights.

Denying women the power and means to control the number and spacing of their children would deny them of their human rights to health, life and equal opportunity. The 21st century must enter history as ending that. Each one of us should help speedup that progress.

Dr. Osotimehin is an Under-Secretary-General of the United Nations and Executive Director of UNFPA, the United Nations Population Fund.