During the twentieth century, life expectancy rose dramatically amongst the world's wealthiest populations from around 50 to over 75 years. This increase can be attributed to a number of factors including improvements in public health, nutrition and medicine. Vaccinations and antibiotics greatly reduced deaths in childhood, health and safety in manual workplaces improved and fewer people smoked. As a result of this - coupled with a decline in the fertility rate (the average number of children that women have in their lifetime) - many major industrial countries are facing an ageing population.
