The rise in emerging nations will accelerate global momentum, while women in dozens of richer countries do not produce enough children to maintain population growth on the basis of Friday figures.
A global overview of birth, death and disease estimates of thousands of databases by country also reported that heart disease was now the world's leading cause of death.
The Institute of Health Metrics and Evaluation (IHME), established by the Bill and Melinda Gates Foundation at the University of Washington, used over 8,000 data sources – more than 600 new – collecting one of the most detailed looks for public health.
Their sources included country studies, social media and open source material.
It noted that although the world's population rose from 2.6 billion in the summer of 1950 to 7.6 billion in the summer, growth and income were very uneven.
The ninety-nine nations, mainly from 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, fertility rates continued to increase as Niger's average woman gave birth to seven children during his lifetime.
Professor Ali Mokdad of IHM's Health Metrics Sciences told AFP that the most important factor in determining population growth was education.
"It's down on socio-economic factors, but it's the task of women's education," he said. "The more a woman is trained, she is spending more time in school, she is delaying her pregnancies, and so there are fewer babies."
IHME noted that Cyprus was the least fertile nation on earth, and the average woman only gave birth once in a lifetime.
In contrast, in Mal, Chad and Afghanistan, women have on average more than six babies.
– "Less mortality, more disability" –
The United Nations predicts that the planet will have more than 10 billion people in the middle of the century, roughly equivalent to IHME's forecasts.
This raises the question of how many people our world supports, that is, the Earth's "carrying capacity".
Mokdad said that as the population of developing countries continues to rise, their economy will generally grow.
This typically has a knock-on effect on fertility over time.
"In Asia and Africa, the population continues to grow and people move from poverty to better income – unless there is war or unrest," he said.
"Countries are expected to improve economically better and more likely fertility will be weaker and weaker."
Except that we now have billions more than 70 years ago, but we also live longer than ever before.
In a study published in the Lancet Medical Journal, the man's waiting time had increased from 71 to 48 in 1950. Women are expected to live up to 76 compared to 53 in 1950.
Longer life brings with it our own health problems when it becomes obsolete and worsens and we are burdened with our healthcare systems.
IHME said heart disease was now the world's leading cause of death. Recently in 1990, newborn diseases were the biggest killer followed by lung disease and diarrhea.
Uzbekistan, Ukraine and Azerbaijan were the highest deaths from heart disease, while South Korea, Japan and France were the lowest.
"You see less mortality in infectious diseases when countries get richer, but also more disability when people live longer," Mokdad said.
He pointed out that although the deaths of infectious diseases such as malaria and tuberculosis have fallen significantly since 1990, new, non-stick killers have taken up the place.
"There are certain behaviors that lead to increased cardiovascular disease and cancer. Obesity is the number one – it grows every year and behavior helps it."