It is estimated that once a country joins the ranks of nations with an extremely low birthrate, the impact on class sizes is felt in all school grades within ten years, on the size of the labor force within 20 years, and on the next generation's birthrate within 30 years.
根據推估，進入「超低生育率國家」行列後，不出 10 年就會影響各級學校的規模；20 年會影響產業的勞動力；30 年會影響下一個世代的出生率；自此國家人口將「越來越少，越來越老」，嚴重影響國力。