It will take only 85 years for the human race to go totally extinct if it (in absence of any obvious medical issues that are understandable) opts to follow their footsteps. Already 59 countries' fertility rates are below sustainable levels of their population. It will have a catastrophic impact on the population and economies of some of these countries.
I thought this information was wrong but I checked it - it is not. Imagine if everyone follows their path - it is an existential threat to mankind. We worry about global warming but are least bothered about dropping birth rates due to declining fertility rate. It is not in 100 years, it may be far less. We will have ghost cities as population rates fall. Negative population growth is a major issue in many countries going forward.
In the west the introduction of birth control has been effective, it has coincided with several major societal shifts. Changing religious values, the emancipation of women and their increasing participation in the workforce, and higher costs of childcare and education have all factored into declining fertility rates.
If this trend is not reversed in two decades there will be massive incentives to get immigrants in at least 30 nations out of the 59 with seriously low fertility rates. It will irk many people but the real issue in the west is to encourage fertility rates so as to have a sustainable population growth and proper demographic structure that may be able to support the unfunded pension liabilities as the baby boomers age.
By 2100, the U.N. predicts that nearly 30% of the population will be made of people 60 years and older. Life expectancy also continues to increase steadily, which means those dependents will be living even longer.
Between 2000 and 2015 the average global life expectancy at birth increased by around 5 years, reaching an average of 73.8 years for females and 69.1 years for males.
With large population soon exiting the workforce, there will be serious productivity losses and a sharp increase of elderly dependent populations resulting in serious economic consequences. Health care costs alone for the elderly will stretch national resources, shrinking younger productive population will have to work much more hours to produce income tax revenue to support the ageing longer living population.