PARIS: The sharp rise in the number of generations in developing countries is fueling global growth, while women in dozens of richer countries do not produce enough children to maintain the population there, according to data released on Friday.
Global review of birth, death and disease rates, which estimate thousands of data sets across countries, has also shown that heart disease is now the only leading cause of death worldwide.
The Institute for Measurement and Evaluation of Health (IHME), founded at Bill and Melinda Gates Foundation at the University of Washington, has used more than 8,000 data sources – more than 600 new – to compile one of the most dazzling views on global public health.
Their sources include country research, social media and open material.
He found that while the world population rose from 2.6 billion in 1950 to 7.6 billion last year, this growth was deeply uneven to the region and income.
Ninety-one people, mostly in Europe and North and South America, did not produce enough children to maintain their current population, according to the IHME study.
But in Africa and Asia the fertility rate has continued to grow, and the average woman in Niger has given birth to seven children during her life.
But Mokdad, a professor of health metrics at IHME, told AFP that the most important factor in determining population growth was education.
"It's socioeconomic factors, but that's the function of female education," he said. "The more women being educated, spending more years at school, postponing pregnancy, and having less babies."
IHME has established that Cyprus is the least fertile nation on Earth, and the average woman born only once in a lifetime.
In contrast, women in Mali, Chad and Afghanistan have on average more than six babies.
The United Nations predicts that by the middle of the century there will be more than 10 billion people on the planet, mostly in line with IHME's projection.
This raises the question of how many people our world can support, known as the Earth's "bearing capacity".
Mokdad said that although the population in developing countries continues to grow, so their economy generally grows.
It usually has a knock-on effect on fertility rates over time.
"In Asia and Africa, the population is still growing, and people move from poverty to better income – unless there are wars or disorder," he said.
"It is expected that countries will be better off economically and that it is more likely that fertility will be reduced and equalized".
Not only are millions now more than us 70 years ago, but we also live longer than ever before.
The research, published in The Lancet Medical Journal, showed that men expect a lifetime of 71 years from 48 years in 1950. Women are now expected to live at 76, compared to 53 in 1950.
Living longer brings our own health problems, getting older and getting worse and putting more burdens on our health systems.
IHME said heart disease is now the leading cause of death globally. As recently as 1990, neonatal disorders were the biggest killer, followed by pulmonary disease and diarrhea.
Uzbekistan, Ukraine and Azerbaijan had the highest rates of heart disease deaths, with South Korea, Japan and France among the lowest.
"You see less deaths from contagious diseases because countries become richer, but more disability as people live longer," Mokdad said.
He noted that although deaths from infectious diseases such as malaria and tuberculosis have been significantly reduced since 1990, new non-transferable killers took their place.
"There are certain behaviors that lead to an increase in cardiovascular disease and cancer. Obesity is number one – it grows every year, and our behavior contributes to it."