The need for sons changes fertility patterns.
Childbearing and fertility patterns have changed greatly since the 1970s.
The UN Population Division's world fertility patterns show that, worldwide, fertility per woman has fallen from 4.7 babies in 1970 75 to 2.6 in 2005-10.
A third group of industrialized countries, consisting of most of eastern Europe along with Japan, showed quite different fertility patterns.
Dependable evidence on historical fertility patterns in Europe is available back to the 18th century, and estimates have been made for several earlier centuries.
Nicholas Eberstadt, a demographer at the American Enterprise Institute, puts it with only mild exaggeration: changing fertility patterns mean that "2,500 years of East Asian family tradition stand to come to an end with the region's rising generation".
The thinktank Institute for Public Policy Research IPPRR) suggests roughly a fifth of the rise in what's known as the Gini coefficient (the standard measure of the gap between the rich and poor) between 1979 and 2003-04 was down to changes in household formation, including the effects of ageing and shifting fertility patterns, but also the rise in single-person households.
Many immigrants, it turns out, quickly adopt the fertility patterns of their new country.
It is, however, not clear whether changing fertility patterns had an impact on female employment behavior.
Projections were carried out for NRR levels from 0.50 to 1.0 and for fertility patterns with a mean age of 25, 29, and 33 years.
We examine whether in-migrants to Kinshasa have different fertility patterns than lifetime Kinshasa residents, and identify characteristics of migrants that may explain differences in fertility.
