Robert EngelmanRobert Engelman

The news was startling: three dozen Kekchi villagers suddenly dead, massacred by soldiers in the Guatemalan mountain town of Panzos. It was 1978 and I was a freelance journalist traveling in the region. Assigned by the Associated Press to investigate the incident, I learned that the indigenous villagers, too crowded to prosper on their tiny farm plots, had been pressuring local landowners for rights to more land—land they argued had once been theirs. Trustworthy sources told me that the landowners had pushed the Guatemalan army to silence the villagers.

More than any other intervention I know of, empowering women through family planning responds to the felt needs of the individual and produces a ripple effect of ever larger benefits for the woman, her family, the community, the nation, and ultimately the world.

The massacre was an outrage and a tragedy. And yet it was in many ways a classic consequence of rapid population growth in a region suffering from overcrowding, shrinking farm plots, soil exhaustion, water scarcity, poverty, desperation, and conflict. The Kekchi families, poor and uneducated and without access to any kind of reproductive health care, had large families; one leader I interviewed was surrounded by his 10 children as we talked. The landowning families, though scarcely wealthy, had somewhat smaller families. The ongoing growth of both groups was clearly stoking land pressure and resource competition that had no non-violent outlet.

A few months later, I met a young Ecuadorian woman who timidly asked me, near the end of an all-night bus ride, to confirm an amazing story she had heard about Americans. Was it true, she said, that an American woman could have sex before marriage with one or more men and eventually marry another? And that she could even tell her husband the truth of her past? I told her it was. "I can't imagine that," she said. "In my culture this is just not possible."

Not until a few years later, still thinking about that woman's repressed and isolated life, did I make a connection between those two situations: women's lack of power in their sexual relationships had everything to do with the environmental pressures behind the Panzos massacre.

I have always been a hiker and backpacker, eager to explore and travel and immerse myself in natural settings. So when I eventually got to report on environmental issues that combined outdoor life with science, health, and medicine, it was a dream job. The link between women's lives and the influence of population dynamics on resource scarcity and conflict lurked in the back of my mind, but I found it difficult to explore it in my reporting.

In the 1980s, any suggestion that population was a problem implied that the solution was population "control"—meaning some kind of governmental coercion to reduce birth rates. Then, as now, that idea was anything but attractive. So when I met Sharon Camp of the Population Crisis Committee and heard from her that population problems would fade away if every woman in the world could decide for herself whether, when and how often to have a child, I was intrigued—and drawn to explore that hypothesis.

The women in my own life have made the case on a more personal level for women's right to make their own life decisions. My strong mother and two sisters made it clear to me from a very young age that they were my equals in every way. I married a woman who shares that view, and she and our daughter are quick to catch me in any false assumptions or hypocrisy with regard to women and gender. These relationships helped sensitize me to the deep social implications—beyond the lamentable personal cost—of any woman's lack of control over her life. The desire to better understand those implications eventually led me out of journalism and into research on and activism for women's reproductive health rights.

What do women want? What men don't have to ask for – the right to have dreams and plans that won't be derailed by a pregnancy they never intended or can't afford or aren't otherwise ready for. Childbearing was extremely dangerous for most of history, a fact women have always known but most men don't think about much. It is also exhausting, and so is raising children, which also takes significant investments of time and money.

When women can choose when to become pregnant, as so many in Panzos could not, they have families appropriate in size for their available resources. Children grow up better cared for and better educated. Women can be more productive outside the home, enabling their communities to become more prosperous and stable. Countries benefit in every way. And the growth of population slows.

Contrary to what some might think, women's search for ways to control the timing and number of their children is not a modern trend: it dates all the way back to antiquity. While doing research for a book on the subject, I learned that women in ancient times used everything from seaweed to crocodile dung to avoid getting pregnant. Some desperate pregnant women would try wild dancing, violence, or drinking some awful mixture to dislodge the fetus. And if the fetus survived to delivery, a last violent resort was, and sometimes still is, infanticide.

Today, I can find no downside to giving all women access to the contraceptives and family planning information they need to safely manage the timing of their childbearing. More than any other intervention I know of, empowering women through family planning responds to the felt needs of the individual and produces a ripple effect of ever larger benefits for the woman, her family, the community, the nation, and ultimately the world. Those benefits can only come from decisions women have the power, autonomy and right to make.

It is a continuing blot on human experience and civilization that so many lives are damaged and lost because women lack the rights and power that men take for granted. Assuring that all women have access to reproductive health and the exercise of reproductive rights is a catalytic and essential first step in righting that wrong.

Robert Engelman is Senior Fellow and former president of the Worldwatch Institute in Washington, DC, and author of More: Population, Nature, and What Women Want.