PARIS (AFP) – Increasing birth rates in developing countries contribute to a global baby boom, while women in dozens of richer countries do not produce enough children to keep population levels there, according to figures released on Friday (November 9).
A global survey of birth, death and disease rates that evaluated thousands of data sets by country also found that heart disease was the only leading cause of death worldwide.
The Institute of Health Metrics and Evaluation (IHME), founded at the University of Washington by Bill and Melinda Gates Foundation, used more than 8,000 data sources – more than 600 of them new – to compile one of the most detailed series of global public health.
Their sources included surveys in the country, social media and open source material.
It found that while the world's population rose from 2.6 billion in 1950 to 7.6 billion last year, this growth was deeply uneven depending on the region and income.
Nineteen nations, mainly in Europe and North and South America, did not produce enough children to maintain their current populations, according to the IHME study.
But in Africa and Asia, fertility rates continued to grow, with the average woman in Niger who gave birth to seven children during her lifetime.
Ali Mokdad, Professor of Health Metrics Sciences at IHME, told AFP that the only important factor for determining population growth was education.
"It's down to socio-economic factors but it's a function of a woman's education," he said. "The more a woman is educated, she spends more years in school, she is delaying her pregnancies and so few children."
IHME found that Cyprus was the least-born nation on earth, with the average woman who only born once in her life.
On the other hand, women in Mali, Chad and Afghanistan have on average more than six children.
"Less mortality, more disability"
The United Nations predicts that there will be more than 10 billion people on the planet in the mid-century, largely in line with IHME's projection.
This poses the question of how many people our world can support, known as the Earth's "force of power".
Mokdad said that while the people of developing countries continue to rise, their economies generally increase.
This usually has a knock-on effect on fertility rate over time.
"In Asia and Africa, the population continues to increase and people move from poverty to better income – if there is no war or anxiety," he said.
"Countries are expected to get better economically and it is more likely that fertility will decrease and be compared." Not only are there a billion more than 70 years ago, but we live longer than ever before.
The study, published in The Lancet Medical Journal, showed that the expected life expectancy for men had increased to 71 years from 48 years 1950. Women are now expected to live to 76 compared with 53 in 1950.
Living longer gives their own health problems, as we age and deteriorate and put greater burdens on our care systems.
IHME said heart disease was now the leading cause of death globally. As late as 1990, neonatal disorders were the biggest murderer, followed by lung diseases and diarrhea.
Uzbekistan, Ukraine and Azerbaijan had the highest death rates from heart disease, where South Korea, Japan and France were among the lowest.
"You see less mortality from infectious diseases as countries get richer, but also more disability as people live longer," said Mokdad.
He pointed out that although deaths from infectious diseases such as malaria and tuberculosis have fallen significantly since 1990, new non-transferable killers have taken place.
"There are certain behaviors that lead to increased cardiovascular disease and cancer. Obesity is number one – it increases every year and our behavior contributes to it."