These changes give poorer countries a demographic dividend.
Combined with effective public policies this time period of the demographic dividend can help facilitate more rapid economic growth and puts less strain on families.
East Asia provides some of the most compelling evidence to date of the demographic dividend.
Ireland also provides a recent example of the demographic dividend and transition.
During the course of the demographic dividend there are four mechanisms through which the benefits are delivered.
There is a strategic urgency to put in place policies which take advantage of the demographic dividend for most countries.
Inevitably the population bubble that made its way through the most productive working years creating the "demographic dividend" grows old and retires.
With a disproportionate number of old people relying upon a smaller generation following behind them the "demographic dividend" becomes a liability.
India's economic prospects pivot in part around what it calls its demographic dividend.
There is a strong demographic dividend in India, where a large proportion of the population is very young.