11/07/2013 07:34 BST | Updated 09/09/2013 06:12 BST

What does Malala Yousafzai's story have to do with World Population Day?

The solution for achieving a sustainable global population lies in allowing women to decide on their own future, respecting their human right to decide on the number, timing and spacing of their children.

Each year on 11 July the international community takes a day to reflect upon the complex and critical relationship between people and the planet. Global population might seem an ethereal concept for some, far beyond the reaches of human influence. But the issue is vital for us all, and it can be steered by a simple set of human rights: the right to choose your partner, your occupation, the number or timing of your offspring and in short, your destiny. This is the same right that the Taliban is trying to deny a generation of young girls in parts of Afghanistan and Pakistan: girls like Malala Yousafzai.

Last year on this day the international community, under the leadership of the British government, took an enormous step in seeking to enable women in the developing world control over their lives and destinies at the London Family Planning Summit. The leaders present made one of the biggest ever international commitments in favour of women's autonomy and reproductive rights. They committed to provide 120million women in the world's poorest countries with access to contraceptives by 2020, effectively eliminating over half of the world's unmet need for contraception in one step. Rarely can a single conference ever have had such a tremendous impact on the lives of hundreds of millions of people, and I am proud to be part of a government that helped to instigate and support such an initiative.

The demographic past of most countries (both developed and emerging ones) will typically show that stabilising population growth is an essential precursor to development. And as the next 50 years of Europe's history are likely to reveal, maintaining a stable population is vital for enabling the society we build to continue to flourish. In addressing these two challenges the world's leaders are facing a variety of pressures that drastically differ depending upon the country, conditions and culture in question.

In some places the population is rising at speed, far surpassing the wishes of mothers, their resources, the local environment's capacity and the public services that are available. Ironically the two most notable causes of this growth are the polar opposites of progress and regression. For thanks to advances in healthcare, food security and sanitation in the world's most disadvantaged countries more children are surviving infancy. But at the same time, in many countries concerted efforts are at work that are actively denying women their reproductive rights and forcing them into a future that is not of their choosing. And statistics published by the UN show that in the developing world there are over 200 million women who want to access modern forms of family planning, but are unable to do so. Over 200 million women are denied the right to control their destiny.

However, many countries are facing the apparently opposite challenge of a declining, ageing population. These countries, like Japan, Italy or Russia, risk not having enough taxpayers to support those requiring public services like education, healthcare or pensions, or enough people to occupy the roles required to enable society to function. Once again this problem has a positive cause, as people are living longer and more people are delaying becoming parents in order first to obtain higher education and achieve a career that they desire. But at the same time there are negative factors contributing to this fall in population such as prohibitively expensive childcare, discrimination against women in the workplace and poverty.

In either of the challenging demographic situations facing the planet at present the complex balance required for a society to sustain and care for itself with a stable workforce is difficult to find. But there is one principle that can apply to both and will greatly help. It is a solution that some countries like Sweden, France and the UK seem to have found. Recent rises in fertility rates in these countries have started to show what can happen when women and men achieve equal status, when parenthood is appealing and a full range of family planning services and supplies are available. Reproductive rights and gender equality are the answer.

This year on World Population Day let us celebrate the unrivalled success that humankind has had in making the world its home, and in enabling civilisation to thrive. But alongside this story of unrivalled success, we must recognise that it has brought with it many challenges that must be confronted if we are to continue to enable all of humanity to thrive, live with dignity and develop. Malala chose not to be one of the 200million women robbed of their destiny. Her future is the world's future, and we must all work together to make it the one that she wants. In the words of UNFPA Executive Director Dr. Babatunde Osotimehin, "Every young girl, regardless of where she lives, or her economic circumstances, has the right to fulfil her human potential. Today, too many girls are denied that right. We can change that, and we must."

It's in all of our interests for us to achieve what we agreed in London a year ago. Let us make the pledges of the London Family Planning Summit a reality.