Beginning around 1800, there was a sharp fertility decline; at this time, an average woman usually produced seven births per lifetime, but by 1900 this number had dropped to nearly four.
从1800年左右开始，生育率急剧下降; 在那个时候，平均每个妇女一生通常生育7个孩子，但到1900年，这个数字已经下降到将近4个。