Despite the huge risks associated with unprotected sex in South Sudan, including an HIV epidemic and one of the highest maternal mortality ratios in the world, the rate of contraceptive prevalence amongst women of childbearing age remains at just 1.7%.
From Scandinavia to France, countries' populations are recovering and childbearing is increasing.
After Ireland's, France's women are the most fertile in the European Union, with 1.9 children per woman of childbearing age.
Yet there is little international evidence that fertility is stimulated by childbearing subsidies; it may not be curtailed by their erosion.
The birth rate has fallen to 1.3 children per woman of childbearing age, down from six in 1960.
It explains why fewer children were born at a particular time, but not why childbearing stayed low.
Many migrants have traditional views on marriage and childbearing.
A report in May from the Japan Policy Council, a research foundation, stated that on current trends some 900 regional municipalities half of the total could disappear or cease to function by 2040 as women of childbearing age migrate to big cities.
According to the latest census, "female literacy, improving general health care, improving female employment rates [are] slowly redefining motherhood from childbearing to child rearing.
Couples in virtually all societies have frequent sex, and therefore access to family planning is necessary to separate sex from childbearing.
They also have high levels of teenage pregnancy that help bump up the figures.Ms d'Addio says the very low fertility rates now seen in many OECD countries are not inevitable, and governments should try to lessen the obstacles to childbearing faced by individuals and families.
