(CNN) Children growing up in Niger are at the highest risk of having their childhood cut short, according to a report by Save the Children .

The nongovernmental organization's report for 2017 ranked the country as the worst place to be a kid, globally.

Norway and Slovenia share the top position as the best places to grow up. (The top 10 best and worst places are listed below)

The End of Childhood Report ranked 172 countries from best to worst in an effort to explore the main reasons why childhood comes to an early end in certain places.

The rankings were determined by measuring the average level of performance across eight topics: under-5 mortality, malnutrition that stunts growth, out-of-school children, child labor, early marriage, adolescent births, displacement by conflict and child homicide.

The United States, at 36th on the list, was not found to be exempt from the threats that contribute to premature death among children. It is one of seven countries where half of all teen births occur, and its number of infant deaths was 23,455 in 2015: more than those of 40 European countries combined in the same year.

Richard Bland, Save the Children's national director of policy, advocacy and development, was most surprised by the country's low ranking and its position between Bosnia and Russia.

The US "is falling behind some countries that have had some pretty severe economic turmoil like Greece or Ireland, and yet a number of those nations are prioritizing childhood," Bland said. "They are investing in childhood and ensuring access to proven programs for childhood."

Bland said the three most noticeable global trends this year that may not have been occurring at as high a rate in past years were violence, famine and displacement.

West and Central Africa, where the 10 worst countries to be a child are located, are particularly affected by famine and displacement, states the report. In Niger, the lowest-ranked country, 43% of children 59 months or younger have stunted growth from malnourishment. The Central African Republic, ranked the fourth worst for children, has 19.3% of its population forcibly displaced by conflict, with evidence of recruitment and use of child soldiers.

"More people are fleeing war and persecution than ever in history," Bland said.

Syria has the highest percentage of a forcibly displaced population on the list, at 65.4%.

In 2015, 263 million children were out of school, 168 million were involved in child labor, and nearly 28 million were forced to leave their homes globally, according to the report.

The 10 countries with the highest child homicide rates are in Latin America and the Caribbean, according to the report. This is due to a combination of gang- and drug-related violence, Bland said.

A positive trend, Bland noted, is that the movement on maternal, newborn and child survival has cut infant mortality by half since 1990.

But he is concerned by President Donald Trump's proposed fiscal budget for 2018, which diminishes foreign aid by 31%. This includes humanitarian assistance as well as maternal and newborn child health programs.

"We're talking about children dying," Bland said. "I mean, there is no greater childhood-ender than mortality and infant mortality, and to us, that's unconscionable to consider cutting programs that have been so successful."

The report lacks an exploration into the root causes of why certain countries made the top of the list or why places like Niger were at the bottom, said Lindsay Stark, an associate professor of population and family health at Columbia University's Mailman School of Public Health.

But it can be assumed that it has to do with levels of economic development, fertility rates and family planning, strong social supports and the absence or presence of conflict, she said.

Save the Children admits that the report has limits, Stark said. A crucial limitation is that the data were drawn from household surveys, missing children who are homeless or living in orphanages, she said.

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"Given what we know about the risks to children who are not even living in a household, I think that this is very true that these are conservative estimates," Stark said.

But Stark approves of how the methodology equally weighed the eight indicators of a childhood's end in order to determine the global rankings.

"Some might say 'if a child dies, that's the end of childhood in a very different kind of way, and so we're going to give that more weight in the index,' " she said. "But Save the Children actually chose to give equal weight, which I personally quite like, because I think it highlights the severity and importance of other issues, which I think might receive less attention."

Best countries to be a kid

1. Norway, Slovenia (tie)

3. Finland

4. Netherlands, Sweden (tie)

6. Portugal

7. Ireland

8. Iceland, Italy (tie)

10. Belgium, Cyprus, Germany, South Korea (tie)

Worst countries to be a kid

1. Niger

2. Angola

3. Mali

4. Central African Republic

5. Somalia

6. Chad

7. South Sudan

8. Burkina Faso

9. Sierra Leone, Guinea (tie)