Fertility and Poverty II

This month the U.S. census bureau released a new report based on surveys done a couple years ago: Fertility of American Women: 2006.

The data, provided by a gazillion women between the ages of 15 and 50, support the well-known trends that women tend to have fewer children when they have more education and more income. But I will argue that the data suggests far more: poor women who have lots of children are poor primarily because of their decision to prioritize children over income, and the fact that they decided to have lots of children has little to do with their innate (genetic) potential to succeed in the quest for material wealth.

My claim rests on the relationship between this perplexing pair of facts:

• Women currently at a low income level are about 60% more likely to have had a baby within the last year as compared to women with much higher [household] incomes.
• Among women aged 40 to 44, the ones currently at a low income level had given birth to only 10 to 15% more children in the course of their entire lives than had women in wealthier income groups.

If poverty causes women to procreate -- and not the other way around -- than the first fact suggests that wealthy women would have far fewer births in a lifetime compared to poor women. However, the second fact shows that there is a very weak relationship between current income and how many births a 40-44 yrs-old women has had. In other words, the poverty of mothers (compared to the wealth of non-mothers) tends to last only as long as these women are raising small children.

The fact that women who have had lots of children do nearly as well financially in later years -- despite the lost income and hours of work during the most intensive parenting years -- suggests to me that these women might be even more innately prone to financial success than the less reproductive women. (Of course, financial success can come in at least two ways: through the development of a career or by a spouse's career.)

Do you think that this is a reasonable interpretation of the data? Check it yourself. Table 2 and 3 discuss lifetime fertility and last-year's fertility, respectively.