07/03/2013 08:41 GMT | Updated 06/05/2013 06:12 BST

Surely a Safety Pin Isn't the Answer for City-Dwelling Teenage Girls Who Are Losing Their Future

Fifteen-year-old Rehana lives in Delhi. The teenager is friendly and intelligent, which means she takes no risks when she goes out on her own in the city. Learning karate and carrying a safety-pin is, she confides, the best way to protect yourself against random oglers and gropers on the bus. Giving them a quick jab with the pin, she says, is the best way to ward them off.

As the Delhi rape case rumbles on, girls in India have become all the more aware of the dangers of large cities. When we talk about the developing world we tend to focus on rural environments, forgetting that the claustrophobic, impoverished chaos of a developing capital can be the most challenging environment of all for a child - particularly a young girl. The news that another girl, this time aged seven, may have been assaulted while at school in Delhi, only proves that these incidents more and more common.

And it's not just Delhi; in many of the world's major metropoli, girls face daily challenges to their safety. The paradox is that while these young women may have more opportunities than their rural peers - better education, for example, or the opportunity to marry later, to someone they love - their worlds are drawing in, not out. Routinely subjected to sexual harassment, exploitation and insecurity, city girls are often afraid to step outside the house alone.

"No-one loves us or helps us," says one Egyptian teenager, poignantly, on her life in Cairo. She is just one of thousands of girls in cities around the world who face daily challenges as they navigate the urban environment around them.

A new study by Plan International talked to over a thousand girls in five major world cities - Delhi, Lima, Kampala, Hanoi and Cairo. We asked them to map out their cities and highlight the dangers. The findings reveal shocking challenges to girls' lives, in which everything from unlit streets and blind corners pose risks to their everyday safety; where girls routinely run the gauntlet of sexual harassment, exploitation and insecurity.

Girls explained that men and boys often take advantage by pressing themselves against them, groping or sexually harassing them as they passed by. They reported harassment by pedestrians, bus conductors, robbers, teenage boys, gangs and factory workers. The city, for many young women, is a hostile environment that is to be negotiated as delicately as a war zone; they hide their bodies, afraid to meet anyone's eye. Most believed it was their fault if they got harassed. Most alarmingly, many drop out of school because it is just too dangerous to get there - like 16 year-old Egyptian teenager Mayada, who left in grade seven because her father thought it too unsafe for her to use the bus.

It's clear that girls' opportunities are being massively affected by all these threats. If a girl gets to secondary school, she increases her and her future family's earnings by as much as 25%; has more of a choice about whether to have a child, is more likely to survive childbirth and her children are more likely to survive beyond five years. If a girl doesn't get an education, the reverse happens.

These are impoverished, unpatrolled areas of major cities that are off the radar, vast slum districts where no registered population figures are ever taken; where girls do not have a voice. Instead, these young women are simply ignored, a hidden generation that is missing out on a viable future.

It is the responsibility of all of us to map out the risks and address them, and to include girls and their concerns in city planning. At the moment, girls and their needs are not factored into the equation, and they should be. Teenagers like Rehana and Mayada; Malala, from Pakistan, now famous for her campaign for education, and collective movements like Billion Rising are building momentum and creating a united voice for change.

We need to back them up; we need to make sure that girls like Rehana no longer feel they have to poke men with a safety pin on the bus to avoid being harassed; we must get them to school on time, as is their right.