By the mid-19th century most of Europe was in the first stage of the demographictransition.
到19世纪中叶，欧洲的大部分地区处于人口转变的第一阶段。
2
To assess the effects of the demographictransition, the two researchers split the sample into women born before 1870 and those born in or after it.
为了评估人口过渡的影响，这两名研究员分头对在1870年前和在这时及之后进行生产的妇女进行取样。
3
Africa, exceptional in so many ways, does not seem to be an exception to the rule that, as countries get richer, they experience a demographictransition.