The adult sex ratio and human population homeostasis

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.