The total fertility rate had been 5.8 in 1950, he notes, and had declined sharply to 2.3 by 1980, just above replacement level.
The U.S. replacement total fertility rate was higher than 2.1 children per woman in the 1800s and early 1900s due to childhood mortality.
When the cohort born roughly in the years between 1993 and 2005 enters prime child-bearing years, there is going to be a pretty significant decline in the crude birth rate even if the total fertility rate (TFR) continues to move modestly higher.
Singapore's total fertility rate of 1.2, which represents the number of children that would be born to a woman if she were to live to the end of her child-bearing years, has been below the population replacement rate for more than three decades.
If the high-fertility nations were to see dramatic declines in Total Fertility Rates (TFRs, the number of children per woman during her reproductive life-time) we would need to see drastic cuts in reproductive rates in at least 40% of all nations and that would have to start today.
The main concern of demographers in their heyday (the 1970s and 1980s) was high fertility and the total number of the world's people.
For example, the interest rate earned by the notional accounts is set by the growth of average wages, not that of the total pay bill, which means that it is unaffected by fertility-induced falls in employment.
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"With only a small variation in fertility, particularly in the more populous countries, the total could be higher: 10.6 billion people could be living on Earth by 2050 and more than 15 billion in 2100, " says the Population Division of the U.N.
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Anna Cristina d'Addio, an expert on fertility policy at the OECD in Paris, thinks they will probably have fewer children in total than if they had started earlier, even though more of them now give birth in their 40s.
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