Every 7 seconds, a girl younger than 15 gets married

One girl under the age of 15 gets married every seven seconds, according to a new report by the international nonprofit Save the Children. The study presents a "girls' opportunities" index of countries, ranking nations on a host of criteria, including access to education and the preponderance of child brides. Nordic countries sit at the top, while impoverished, fragile states such as the Central African Republic, Niger and Chad hold up the bottom.

According to UNICEF data, more than 700 million girls today were married before their 18th birthday - and one in three of them was married before she turned 15. They are often forced into these marriages, almost invariably to older men. The bulk of them live in relatively poor, rural communities in South Asia and parts of Africa. In many instances, these unions take place in contravention of local laws.

Despite global efforts to combat the enduring practice, Save the Children estimates that the total number of women married in childhood will grow to 950 million by 2030 and to 1.2 billion by 2050. There's a link between statistics on child marriage and a country's faltering development. And girls who are subject to such marriages often are more vulnerable to abuse and trafficking, as well as the risk of maternal mortality.

"Child marriage starts a cycle of disadvantage that denies girls the most basic rights to learn, develop and be children," Helle Thorning-Schmidt, the chief executive of Save the Children, said in a statement. "Girls who marry too early often can't attend school, and are more likely to face domestic violence, abuse and rape."

The international organization found that girls are more likely to be forced into child marriages in conditions of poverty, humanitarian disaster and conflict. Save the Children pointed to an upswing in girls in Syria being married off as their families cope with life in the shadow of their country's ruinous civil war. In Sierra Leone, an Ebola outbreak shut down schools and led to an estimated 14,000 teenage pregnancies.

The number of child brides is particularly high in South Asia, where the population is large and the practice difficult to stamp out in more impoverished areas. There remains an entrenched rural-urban divide with regard to the preponderance of girls being married as children.

And incidents of child marriage increase where there is less access to education.

In the index compiled by Save the Children, the United States ranks at a rather lowly 32, beneath nations such as Kazakhstan and Algeria. This is largely because of the country's relatively high rate of teenage pregnancy and slightly higher rates of maternal mortality compared with those in other developed countries.