联合国预测，到2080年代世界人口将达到103亿的峰值，由于生育率下降，到2100年将下降到102亿。 UN predicts global population to peak at 10.3 billion by 2080s and decline to 10.2 billion by 2100 due to lower fertility rates.

联合国预测，到2080年代世界人口将达到103亿，在达到峰值后，到2100年下降到102亿。 The UN predicts the global population will reach 10.3 billion by the 2080s, peaking before declining to 10.2 billion by 2100. 人口峰值提前到来的原因是大国（尤其是中国）的生育率较低。 This earlier-than-anticipated population peak is due to lower fertility rates in large countries, particularly China. 全球妇女平均生育的孩子数比1990年少一个，超过半数国家每名妇女平均生育的活产孩子数低于不移民情况下维持人口所需的2.1个。 Women globally have an average of one fewer child than in 1990, and over half of countries have an average number of live births per woman below the 2.1 needed for population maintenance without migration. 报告还指出，63个国家的人口已经达到峰值，预计未来30年这些国家的人口将下降14%。 The report also states that population has already peaked in 63 countries, with a projection of a 14% decline in the next 30 years for these countries.