Opinion piece by Dr. Babatunde Osotimehin, Executive Director of UNFPA, and Phumzile Mlambo-Ngcuka, Executive Director of UN Women

We all remember when the headlines, nearly half a century ago, warned of an imminent population explosion. Governments were scrambling to find the solution and their answer was to limit population growth, especially in the developing world. In 1994, we found what then seemed like an unlikely answer to dealing with changing population dynamics: women.

The International Conference on Population and Development (ICPD), held in Cairo in1994, made news when a number of women groups were able to successfully convince governments of this proposition and shift the debate from population control to women’s empowerment. They were successful because they argued that an investment in women’s health and education would lead to economic development.

And they were right. During the past 20 years, fertility rates have generally declined as women’s rights and opportunities have improved. The just-released ICPD Beyond 2014 Global Report notes that high fertility rates of 4 children or more per woman are now confined to just 45 of the world’s poorest nations, down from 81 nations in the period 1990-1995. These latest statistics suggest that progress has been made, but that more work is needed.

The ICPD report confirms that in most parts of the world today, sexual and reproductive health services have improved significantly, fewer women are dying while giving birth, and more women have access to education and jobs. Much of this has been achieved through the interventions of governments and their partners, including international agencies such as the United Nations, global philanthropic foundations and other non-governmental organisations.

But if so much progress has been made, why are so many women still struggling to realise their full human potential? A key reason is the stubborn persistence of poverty and gender inequality.

There is not a single nation on earth where women enjoy economic and political power equal to men. But meaningful progress in many nations has empowered a new generation of women who are exercising greater control over their social, economic and reproductive lives. Unfortunately, however, such progress toward gender equality is not universal. In the last two decades, religious and political divisions have grown wider, both between and within nations, with the human rights of and autonomy of women and girls a frequent touchstone of ideological differences. Sadly, women, and especially adolescent girls, have often paid the biggest price in these culture wars.

Today, one in three women worldwide reports having experienced physical and/or sexual abuse. A recent (2013) UN multi-country study on men and violence in Asia found that nearly half of the 10,000 men interviewed reported using physical and/or sexual violence against a female partner. And nearly a quarter of the men interviewed admitted raping a woman or girl.

Also contributing to gender inequality is the indefensible tolerance for child marriage in a number of societies and cultures. In 41 nations, more than 30 per cent of girls marry before 18, and in most cases, these girls will miss opportunities for education and personal growth that would open doors for them in both society and the workforce.

As the new ICPD report makes clear, a nation’s development potential is, in many ways, directly linked to the opportunities it offers to its poorest and most marginalised people, especially its women and girls. Nations that stumble on issues of gender equality are more likely to fall behind their neighbours in global development.

The challenge for the next 20 years, then, is clear. Nations committed to economic growth must put outdated prejudices and cultural preconceptions about the role of women behind them and embrace gender equality in both law and custom. In the final analysis, affording equal rights and offering equal opportunities to women is not just the right thing to do, it’s also the smart thing to do as the experience of the past two decades has shown.

This opinion piece originally appeared on Al Jazeera