A World Health Organization (WHO) report showed that life expectancy is up across the globe.

A girl born in 2012 is expected to live for 73 years and a boy 68, six years longer than they would have lived if born in 1990, a WHO news release reported.

"An important reason why global life expectancy has improved so much is that fewer children are dying before their fifth birthday," Doctor Margaret Chan, WHO Director-Genera, said in the news release. "But there is still a major rich-poor divide: people in high-income countries continue to have a much better chance of living longer than people in low-income countries."

Most deaths in children under five occurred as a result of premature death (17.3 percent) or pneumonia (15.2 percent).

A boy born in 2012 in a high-income country has a life expectancy of about 76 years, which is 16 years longer than a male born in a low-income country.

"In high-income countries, much of the gain in life expectancy is due to success in tackling noncommunicable diseases," Doctor Ties Boerma, Director of the Department of Health Statistics and Information Systems at WHO, said in the news release. "Fewer men and women are dying before they get to their 60th birthday from heart disease and stroke. Richer countries have become better at monitoring and managing high blood pressure for example."

Low-income countries have made the most progress in recent years. Liberia had a 20-year increase (from 42 years to 62 years) between 1990 and 2012.

Women in Japan have the longest life expectancy (87 years) while men and women living in nine sub-Saharan African countries have the lowest (about 55 years).

The top three causes of premature death worldwide were "coronary heart disease, lower respiratory infections (such as pneumonia) and stroke," the news release reported.