UNICEF's analysis focused on children's chances of escaping extreme poverty, getting a basic education and avoiding a violent death. It showed that 37 countries have seen a clear decline in at least one of those areas in the past two decades. The main causes? Unrest, conflicts, financial crises and poor governance.

There have been major efforts to improve child welfare around the world over the past two decades. But despite progress, millions of children still face massive challenges caused by factors outside of their control. According to a 2017 UNICEF report, one in 12 of the world's 2.2 billion children has far bleaker prospects today than the previous generation did 20 years ago.

According to UNICEF, the Central African Republic, South Sudan, Syria and Yemen — all countries experiencing major conflict — have seen a decline across more than one of the three areas measured. The most dramatic change, however, was recorded in the world's newest nation, South Sudan.

South Sudan was the only country where children fared worse in all three categories than previous generations. After gaining independence in 2011, the country has been plagued by civil war and famine. Four-year-old Adeng Macher, pictured above, is one of an estimated 2 million people who are near starvation.

Violent deaths among children below the age of 19 have increased in seven countries: Central African Republic, Iraq, Libya, South Sudan, Syria, Ukraine and Yemen. Above, armed Yemeni children ride in the back of a truck with soldiers loyal to President Hadi. The UN says hundreds of children have been killed in the country since 2015, while more than 1,000 have been recruited as child soldiers.

The share of people living on less than $1.90 (85 euro cents) a day has increased in 14 countries, including Benin, Cameroon, Madagascar, Zambia and Zimbabwe. According to the UN, around 19 percent of the world's children live in extreme poverty.

The number of children getting a primary school education has dropped in 21 countries, including Syria, Bolivia, Jordan and Tanzania. The problem is most acute in West and Central Africa. Above, students take part in an English class in Bentiu, South Sudan, in 2011. Violence in the country has forced a quarter of schools to shut down, preventing an estimated 2 million kids from attending class.

UNICEF's report was released on World Children's Day, which celebrates the anniversary of the adoption of the Convention on the Rights of the Child on November 20, 1989.

According to the International Labour Organization (ILO), agriculture is where the worst and most common forms of child labor are found. Coffee plantations employ children to pick beans in Colombia, Tanzania, Kenya, Uganda, Mexico, Nicaragua, Dominican Republic, Honduras, Panama, El Salvador, Guinea, and Ivory Coast.

Cotton-picking is done by children all over the world, but particularly in countries whose economies rely heavily on its harvest - like in Ivory Coast, where it provides a livelihood for 3 million people. According to the NGO Cotton Campaign, it is also a major problem in Uzbekistan and Turkmenistan, where children are sometimes forced to work in the cotton sector.

The US Department of Labor lists 15 countries using child labor to produce bricks for construction projects. These countries include Argentina, Brazil, China, Ecuador, North Korea and Peru.

Perhaps most famous for its oppressive sweatshop conditions in Cambodia and Bangladesh, the garment industry employs children all around the world. Here, Syrian refugees, including children, are seen producing shoes in Gaziantep, southeastern Turkey.

Sugarcane harvesting is carried out by children in countries such as Guatemale, the Phillipines and Cambodia, amongst others. ILO found thousands of children working in sugarcane production in the Phillipines, some as young as seven years old.

ILO says that the tobacco industry is one of the most hazardous for child workers due to the long hours, extreme heat, exposure to dangerous chemicals, having to carry heavy loads and risk of attack from animals. The average child worker in the tobacco industry works around 10 hours a day.

Child labor in mines, particularly gold mines, is common in some parts of Africa, Asia and South America. Children either risk death from explosions in mine shafts, or must stand for hours in riverbeds sifting for small nuggets of gold. Because of unclean water, the children working in the gold industry are at high risk of contracting dysentery, malaria, meninigitis and tuberculosis.