That said, given the TFR is a synthetic measure of the sum of age-specific fertility rates, and does not consider the size of the reproductive cohort, nor take into account any tempo effects, future TFRs are able to 'catch up' as childbearing intentions are realised later in life, as with the emergence of Gen TGYH.
Once the baby bust cohort reached around 30 years of age and the postponement of childbearing slowed (but not for all), the decline in total fertility rates began to reverse and Gen TGYH was born.
Costello suggested that any benefits associated with an increase in fertility would not be realised for 20 years after their birth when they reached working age, and the evidence so far suggests that he was right: Gen TGYH will enter the workforce as the last of the Baby Boomers are reaching retirement age.
In contrast, despite their relative youth, Gen TGYH is already a generation; they are defined by the current demographic context to which they were born, and a future economy into which they will grow.
Just as the Baby Boomers and Generations X and Y have become defined in contrast to the attitudes, behaviours and qualities of their parents before them, so too will Gen TGYH. Gen TGYH are the sons and daughters of the post the 1970s generations--Generations X and Y--who themselves have renegotiated the life course (McKay 1997).
Interestingly, Gen TGYH is being born to both Generation X and Generation Y women who have typically delayed motherhood by compressing their critical childbearing years into a shorter period of time (ABS 2011).
By the early 2000s, TGYH had become a well-adopted strategy of China's foreign policies as more officials and scholars use this term to describe China's national policy towards the outside world.
However, the exact meaning of TGYH is heatedly debated in China and the West.
To summarise, since its conception, the actual meaning of TGYH has undergone some changes, although all Chinese leaders, to varying degrees, have categorised it as being China's guiding principle in its foreign behaviours.
There are still heated debates about the TGYH strategy within the Chinese foreign policy establishment.
Although opponents of TGYH list many faults about the TGYH, there are, in general, four main reasons why they think TGYH should be abandoned or at least modified significantly.
In sum, opponents of TGYH believe that China's national power has already reached a point where it needs to be more proactive regardless of its intentions.