A new study reveals huge strides in reducing the global infant mortality rate -- and also highlights some longstanding roadblocks.

UNICEF's "2012 Progress Report on Committing to Child Survival: A Promise Renewed" ranked 195 countries on their infant mortality rates. The study ranked the countries in terms of the greatest and least probability that a child born in that nation will make it to the age of five.

The report reveals that while global progress is commendable -- more children now survive their fifth birthday than ever before -- the poorest nations still lose the greatest number of children to preventable causes.

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"The economically poorest regions, least developed countries, most fragile nations, and most disadvantaged and marginalized populations continue to bear the heaviest burden of child deaths" Anthony Lake, Executive Director of UNICEF, stated.

More than four-fifths of all under-five deaths in 2011 occurred in sub-Saharan Africa and South Asia, according to the report.

Organizations such as UNICEF continue to galvanize global leaders to tackle the issue. Under UNICEF's A Promise Renewed campaign, more than 100 governments and many civil society and private sector organizations have signed a pledge to redouble their efforts for child survival with the hope that no child need die of preventable causes.

Scroll through some of the world's best and worst countries for infants below.

Note: Of the 12 countries that have the lowest rates of infant mortality, numbers 12 to 2, all have a uniform ranking.

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  • The Worst Infant Mortality Rates: 1. Sierra Leone

  • 2. Somalia

  • 3. Mali

  • 4. Chad

  • 5. Democratic Republic of the Congo

  • 6. Central African Republic

  • 7. Guinea-Bissau

  • 8. Angola

  • 9. Burkina Faso

  • 10. Burundi

  • The Best Infant Mortality Rates: 12. Andorra

  • 11. Cyprus

  • 10. Finland

  • 9. Iceland

  • 8. Japan

  • 7. Luxembourg

  • 6. Norway

  • 5. Portugal

  • 4. Singapore

  • 3. Slovenia

  • 2. Sweden

  • 1. San Marino