Girls may run the world, but they're also up against major inequality -- and they could use more support.

July 11 is World Population Day, an annual U.N. event that focuses on the urgent issuesaffecting the world's booming population. This year's theme is "investing in teenage girls" -- a call for attention and action on this particularly vulnerable part of the global population.

Of the more than 7 billion people in the world, approximately 1 billionare young girls between the ages of 10 and 24. And they're facing some big challenges, from high rates of child marriage to inadequate health care access.

The stats don't lie: Many of the most pervasive inequalities facing the world's girls stem from a lack of reproductive health care and education.

Here are seven reproductive health issues impacting the lives of teen girls globally -- and what you can do to help.

1. Concerning rates of child marriage around the world

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Today, 1 in 3 girlsin developing nations are married by the time they're 18 years old. But child marriage is a global issue, prevalent (though perhaps less expected) in Western countries, too. Advocates say child marriage a human rights violation, and is often a major contributing factor in further inequality in a young girl's life.

High rates of child marriage set the stage for many reproductive health issues, especially in developing nations. When girls are expected to marry young, they're expected to start families young -- and that can have devastating impacts. Complications due to childbirth are a leading cause of death for girls age 15 to 19, and an estimated 39,000 girlsmarry too young every day.

What you can do:Donate to organizations tackling the issue head-on. UNICEFand CAREfocus on the broader needs of teen girls globally, but also tackle the issue of child marriage closely.

You can also donate to the International Center for Research on Women, one of the leading global organizations for curbing child marriage through research initiatives.

2. The continued practice of female genital mutilation

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Female genital mutilation (FGM) is any procedure that intentionally alters or causes injury to the female genital organs for non-medical reasons.

It's a human rights violationthat is performed around the world, yet most heavily impacts teen girls in Africa, the Middle East and Asia. The practice is carried out globallyas a way to control a woman's sexuality and ensure purity for marriage.

More than 200 million girls and women alive today have been subjected to the practice, with most being cut between birth and 15 years of age. While there are no health benefits to the procedure, the risks can be devastating. FGM can cause severe bleeding, problems urinating, cysts, infections, complications in childbirth and even death.

What you can do:In conversations around FGM, it's essential to realize all forms of the practice are a human rights violation -- even when performed by a health care professional. Advocate for an end to female genital mutilation by supporting organizations that work to end the practice completely.

The Global Alliance Against Female Genital Mutilationand the Orchid Projectare working tirelessly to end the practice through on-the-ground work and community partnerships. To educate yourself on the impacts of female genital mutilation, visit here.

3. High rates of sexual violence

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Sexual violence is prevalent in all regions, making it one of the biggest threats to a young girl's well-being. It not only has an impact on a teen survivor's emotional and physical health, but also her reproductive health.

It's estimated that 1 in every 3 women globally will experience physical or sexual violence in her lifetime. Young women who are survivors of sexual violence are at an increased riskof contracting sexually transmitted diseases, such as HIV, which can lead to death in developing nations without access to antiviral medication. Sexual violence can also result in early pregnancy and trauma, which can affect a girl's sexual well-being for the rest of her life.

In the United States, 1 in every 6 womenhave experienced some form of sexual violence. Of those women, 15% were between the ages of 12 and 17 when the violence occurred.

Sexual violence also materializes globally in the form of forced prostitution -- whether through human traffickingor being locked out of economic opportunity.

What you can do: Donate to organizations looking to educate and provide solutions to curb the impact of sexual violence.

In the U.S., RAINNis a leader in sexual assault education and public policy solutions, also providing a helpline for survivors.

Equality Nowand Plan Internationalfocus on education around sexual violence and connecting with local activists to enact policy changes in their own communities.

It's also essential to pay attention to intersecting issues and identities that make some groups of teen girls particularly vulnerable to sexual violence. In the United States, for example, indigenous girls and women are 2.5 times more likelyto be sexually assaulted that non-Native women and girls. In developing nations, girls who lack close water access are often targets of sexual harassment and violencewhen going to fetch water for their families.

Curbing sexual violence helps solve seemingly unrelated inequalities for women around the world.

4. Unmet needs for family planning methods and health education

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According to the U.N., more than 225 million women and girlshave an unmet need for modern family planning methods, such as birth control, IUDs and condoms. There's also a lack of access to education on pregnancy, childbirth and reproductive health.

It's a particularly pressing issue in developing nations, where pregnancy for teen girls is extremely prevalent and dangerous -- pregnancy and childbirth are the leading cause of deathfor women and girls in developing countries. But the threat to family planning methods, like access to contraception and safe abortions, extends to the developed world, too.

Recent legislation in Texas, though deemed unconstitutional, has tried to restrict women's access to family planning in the U.S. And countless hurdles in abortion accessare a reality for women in several U.S. states.

But research shows that women's lives are greatly improved, particularly in terms of education and income, when they control their own reproductive health -- and it all starts with knowledge and access.

What you can do:Advocate for a woman's right to her reproductive health in your community by becoming familiar with localand globalpolicies and access. But go beyond that, if you can, and contribute monetarily to those working to increase access globally.

Charities such as Global Fund for Womenand Pathfinder Internationalwork on the grassroots level with campaigns to widen education and access for women around the globe, especially concentrating on developing nations.

5. Lack of access to menstrual products

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Menstruation impacts the majority of the world's teenage girls, but they aren't always equipped to deal with their monthly cycle. In many poor countries, girls lack access to period products, like tampons and pads, that help make menstruation more manageable.

Girls in poor nations often rely on rags, pieces of old mattresses and newspaperin lieu of modern period products. And that has devastating impacts on girls' education; an estimated 1 in 10 teen girlsin Africa skip or drop out of school because they don't have access to period products.

Poor teens in developed nations also feel the strain of expensive products. An average box of tampons or pads can cost around $5 to $10, plus tax. Even in public restrooms, a single pad or tampon, which can be used for around 8 hours at most, will set you back at least 25 cents. Over the course of a week-long cycle, that money adds up fast. Poor girls in developed countries use similar solutions to women in developing regions to cope with menstruation -- and they risk infection while doing so.

What you can do:Donate to organizations working to increase access to menstrual products globally. Lunapadsworks to provide reusable, washable cloth pads to girls in developing nations. Femme Internationalprovides sustainable menstrual cups to girls in developing countries, while also educating communities about menstruation to dispel stigma around the subject.

Also consider buying your period products from companies invested in giving back. Conscious Period, for instance, donates period products to homeless women for every purchase made -- and they create sustainable products that are good for the environment. You can also donate menstrual products directly to local homeless shelters.

6. Lack of access to adequate maternal health care

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Maternal health care is essential to a successful pregnancy and birth. About 16 million girlsbetween the ages of 15 and 19 -- and an estimated 1 million girls under 15 -- give birth each year. As a result, access to maternal health care is crucial, given the high rates of complications for adolescent pregnancy.

In developing nations, lack of access to health care can stem from economic barriers, overwhelmed medical facilities or physical distance -- and all sources have devastating impacts for pregnant girls. Lack of access to proper maternal health care can lead to complications during pregnancy or birth, and even deathfrom undiagnosed medical complications.

Maternal health care can help curb infant mortality, too. A child is about 500 timesmore likely to die in the first day of life than the first month of life due to complications during birth.

What you can do:Donate to organizations working to make a tangible, sensitive impact.

Engender Healthand UNICEFwork to ensure health facilities are equipped with supplies and well-trained staff, while also advocating for global policy shifts to tackle the issue of maternal health care. The international nonprofit Women Deliverworks to tackle the issue of maternal health through various campaigns and an international conference, which brings together women to share solutions, build coalitions and drive progress.

Clean birthing kits make a world of difference for women in need. Kits consist of six items: a bar of soap, a plastic sheet to deliver on, gloves for those aiding in delivery, a razor blade to cut the umbilical cord, an umbilical tie and a clean cloth. The United Nations Population Fund provides three kits to women in need for every $11 donated to its efforts. You can donate here.

7. Concerning rates of maternal mortality

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A lack of access to medical professionals creates a very real risk of death during childbirth. Every day, around 800 girls and women diefrom preventable pregnancy and childbirth-related causes. The majority of those deaths -- a staggering 99% -- occur in developing nations.

Young girls, whose bodies often aren't ready to handle the immense stress of childbirth, face a higher risk of complications and death as a result of pregnancy than older women.

The main causesof maternal mortality are severe bleeding, infections, high blood pressure during pregnancy, complications from delivery, and unsafe abortions. In fact, women and girls in sub-Saharan Africa are as likely to diein pregnancy or childbirth as women in 19th-century England.

What you can do:Donate to organizations working to curb rates of maternal mortality through broadening maternal medical access. Every Mother Countsworks to provide women and girls with transportation to medical facilities, educates birthing attendants, and provides birthing supplies to medical professionals. CAREand UNICEFare also on the front lines of tackling the issue.

And clean birthing kits are, again, essential for curbing infection rates for girls as they wait for medical facilities to meet their needs. Donate hereto help.

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