Unemployment Linked to Drop in Fertility
Understanding trends in fertility is one of the most important tasks for demographers. Population growth, or the lack thereof, is linked to economic activity. For instance, as a general rule, wealthy countries have lower fertility rates than poor ones. That is why the "problem" of overpopulation is a self-correcting one; as the developing world becomes more advanced, we will expect its fertility rate to fall.
A new paper published in PNAS adds another layer of complexity to the fertility picture. The authors, both from Princeton University, established short- and long-term links between a rise in unemployment and a drop in fertility. Using birth records, they analyzed over 110 million conceptions in American-born women between 1975 and 2009. (Immigrants were excluded because it was not possible to determine when they had children. They also tend to have more children than the native born.) Women were divided into cohorts based on age and state of birth, and the unemployment rates for the mothers' states of birth were used in the analysis. (The authors note that, while it is true future mothers can move to different states -- perhaps ones with lower unemployment -- most (roughly 2/3) remain in the states in which they were born.)
Their analysis shows a clear correlation: As unemployment increases (x-axis), conception rates drop (y-axis) in every cohort, except women aged 40-44. The biggest drop occurred in women aged 20-24.
Further analysis showed that women who experienced a period of higher unemployment from the ages of 20-24 were likelier not to have any children at all. Specifically, the authors estimate that, if unemployment rises by 1 percent, 5 more women per 1,000 will choose to remain childless. The authors admit that the overall effect of the unemployment-fertility link on society, however, is small: The total number of conceptions for American-born women is 1,916 per 1,000; women aged 20-24 are predicted to have only 14 fewer conceptions for every 1 percentage point increase in unemployment.
Small though it is, the trend is real. The authors created a "big picture" graph, showing how the conception rate falls as the national unemployment rate rises. (The blue rectangles indicate recessions.)
But note that the overall trend in conception rate is down. That is because there are likely other factors at play.
As discussed above, wealthier countries have fewer children. The United States has grown wealthier since 1975. The following chart, from Wolfram Alpha, shows how real GDP per capita (measured in constant 2005 dollars) has increased from $24,601 in 1975 to $49,506 in 2007.
Furthermore, female education is linked to a drop in fertility. The percentage of American women aged 25-29 who hold a bachelor's degree has increased from under 15% in 1969 to nearly 35% in 2009, as depicted in this graph from the Population Reference Bureau:
Thus, it is quite likely the long-term drop in conception rate among American-born women has multiple causes. It would be interesting to know which of these factors has the greatest impact.
Source: Janet Currie and Hannes Schwandt. "Short- and long-term effects of unemployment on fertility." PNAS. Published online before print: 29-Sept-2014. DOI: 10.1073/pnas.1408975111