Koeslag J H
S Afr Med J. 1981 Oct 24;60(17):666-9.
About 50% of Swedish infants born in 1750 survived to have children themselves, and when they did they produced about 4 babies per family. In 1970 nearly all infants born could be expected to survive to adulthood, and about 2 babies were produced per family. This matching of the fertility rate to the childhood mortality rate could be the result of changes in the adult sex ratio.
1750年出生的瑞典婴儿中，约50%存活至成年并育有子女，且他们每个家庭平均生育约4个孩子。1970年，几乎所有出生的婴儿都有望活到成年，每个家庭平均生育约2个孩子。生育率与儿童死亡率的这种匹配可能是成年性别比变化的结果。
