most of the past century, there has been a negative relationship between economic development and human fertility.They found that the fertility rates of countries are linked to their Human Development Index (HDI), which evaluates life expectancy, average income, and education levels, and that in some countries, particularly those with an HDI of over 0.9, fertility rates have begun to increase and, in some cases, are approaching two children per woman.While there are some exceptions, such as Japan, it appears that higher levels of wealth and education can ultimately lead to a desire for more children.