BABY! -BOOM!?- BUST!?

STUDY : BABY boom for some nations, BUST for others.

LESS MORTALITY  MORE DISABILITY : The united Nation predicts there will be more than 10 billion humans on the planet by the middle of the century, broadly in line with IHME  projections.

This raises the question of how many people our world can support, known as Earth's  ''carrying capacity''.

Soaring birth rates in developing nations are fuelling a global baby boom while women in dozens of  richer countries aren't producing enough children to maintain population levels there, according to figures released Friday.

A global overview of birth, death and disease rates evaluating thousands of on country-by-country  basis also found that heart disease was now thee single leading cause of death worldwide.

The Institute for Health Metrics and Evaluation [HME], set up at the University of Washington by the Bill and Melinda Gates Foundation, used more than 8,000 data to compile one of the most detailed looks at global public health.

Their sources included-in-country investigations, social media and open-source material.

It found that while the world's population skyrocketed from 2.6 billion in 1950 to 7.6 billion last year, that growth was deeply uneven according to region and income.

Ninety-one nations, mainly in Europe and North and South America, weren't producing enough children to  sustain their current populations, according to the IHME study.

But in Africa and Asia fertility rates, continued to grow, with the average women, in Niger giving birth to seven children during her lifetime. 

Ali Mokdad, professor of  Health Metrics Sciences at  IHME, told AFP that the single most important factor in determining population growth was education.

''It's down to socioeconomic factors but it's a function of woman's education,'' he said. ''The more a woman is educated, she is spending more years in school, she is delaying her pregnancies so will have fewer babies.''

The IHME found that Cyprus  was the least fertile nation on earth, with the average woman giving birth just once in her life. By contrast woman in Mali, Chad and Afghanistan have an average of more than six babies.

Mokdad said while population in developing nations continue to rise, so in general are the economies growing.

This typically has a knock-on effect on fertility rates the over time. [Agencies].