There are a few puzzles in the latest news on U.S. fertility trends.
The issues behind fertility trends and patterns are complex, reflecting changing social and well as biological influences, and demanding careful attention to methods. Birth rates can be measured as annual events (such as the percentage of women having a birth in a given year) or as life-course outcomes (such as the percentage of women who reach age 45 without ever having a birth). Comparisons over time are confounded by changes in the composition of the population with regard to age, and some subgroups are subject to changing composition as a result of social or cultural, rather than biological, trends. For example, consider that a woman may spend the years from age 22 to age 43 as a college graduate, and then register an advanced degree at age 44. That means her births in the previous 20 years count among those with BAs, while her “completed fertility” would be counted among those with advanced degrees.
It’s been a confusing few days for fertility-news watchers, so I’ll try to muddle it up a little more. I ran some numbers for a conversation I had with New York Times Upshot reporter Claire Cain Miller, which she reported under the title, “Births to Single Mothers Are Down, Except for Those 35 and Older.” I’ll show those here. They go along with the various headlines about Gretchen Livingston’s new Pew report, “Childlessness Falls, Family Size Grows Among Highly Educated Women,” reported by Brigid Schulte as, “Why educated women are having more babies.”
Here’s Miller’s chart, based on federal registered birth data. Note these are birth rates for women who aren’t married, which is not the same as the percentage of births occurring to women who aren’t married:
For unmarried women of all ages except 15-17, birth rates increased from 2002 to 2007. As I’ve shown before for women overall, the trend shows the increasing delay of childbearing, with a steeper rise for women ages 30-34 than for those in their early 20s. After 2007, however, reflecting the recession, birth rates fell for all unmarried women except those ages 35 and up. The conventional explanation for this has been that individuals and couples delayed births when they were financially squeezed, but those running up against the end of their fertile years couldn’t delay without risking infertility.
To see how this is working for single women in particular (and single here includes those who are cohabiting), it’s helpful to break it down by age and education. Older women face the biological clock issue regardless of their education level, and women with less education had greater exposure to recession-related hardship. What I showed Miller was this chart, which I made from American Community Survey (ACS) data provided by IPUMS.org. The solid lines are all unmarried women ages 15-44 — red for less than BA, blue for BA plus — while the dotted lines are just the older subgroup, 35-44. This shows that the volatility is greatest for women without BAs. And there is no real recession decline for the 35+ groups:
Based on that, Miller wrote:
During the recession, the decline in single motherhood was entirely attributable to women without college degrees, according to census data analyzed by Philip Cohen, a sociologist at University of Maryland who writes a blog called Family Inequality.
These are “women for whom the hardships of single motherhood are most acute,” Mr. Cohen said. “This could be deliberate planning, or it could reflect relationship problems or economic stress undermining their family plans.”
Among older women who are unmarried, ages 35 to 39, however, the birthrate was 48 percent higher in 2012 than in 2002, according to the National Center for Health Statistics. The increase was driven by college-educated women, according to Mr. Cohen’s analysis. “The delay in general fits a long-term pattern: that family formation is increasingly delayed until women are more established, spend more time in education and more time developing their careers,” he said.
This is tricky because of course single women without BAs do have higher birth rates, so it’s not like poor women just can’t afford to have children — but as a group they were affected more by the crisis. What that means is that a greater proportion of them were affected in such a way as to reduce their fertility than among other groups.
Although it seems contradictory on the surface, this is consistent with Livingston’s headline: Childlessness Falls, Family Size Grows Among Highly Educated Women. Although my figure only shows single women, look at the BA-holding 35+ women: their birth rates rose about 50% from the beginning of the decade till the recession, from about 10 per 1000 to about 15 per 1000, a rate they held through the recession.
But Livingston’s data are “completed” cohort fertility — estimated by the number of children women have had when they’re surveyed in the ages 40-44. Here’s her rather shocking chart:
My chart was annual birth rates. But hers is more interesting because it captures the life course more. What is it that is making women with advanced degrees have bigger families — and making fewer of them have no children at all?
There are several tricky things here, which I’ll show with data in a minute. They are:
- The advanced-degree group has grown less select as it has grown — more women are entering this category. In particular, there are more Black and Hispanic women going beyond BAs, as well as presumably more women from poor backgrounds. So that might increase the birthrates of the group.
- On the other hand, although marriage is more common among women with more education — and growing increasingly so — the proportion married among women going for advanced degrees has still fallen. Since married women have more children, this should lower fertility of higher-education women. (A quick check shows a slight decline in the proportion married among advanced degree holders under age 45 from 1990 to 2013, from 68% to 66%.)
- Finally, as more women get BA degrees and go straight into additional schooling, the average age of women getting advanced degrees has fallen. That gives them more time to rack up births before hitting 44. (To make matters impossibly complicated, if they hold off on having children till they finish their advanced degrees, they will probably be younger when they graduate, as some graduate students with children might tell you.)
Remember that people make decisions about childbearing and education at the same time. If more women decide to get advanced degrees with the goal of having more children from a position of strength, then the statistics will show more women with advanced degrees having children — even if the decisions weren’t made in the order we assume.
It’s hard to get at this with the data we have. The population data we have on education and family characteristics doesn’t tell you when people got their degrees, which means those late 44-year-old medical school graduates are hard to pin down. Ideally, then, we’d have a measure of who is attending school, which would tell us who is on the way toward a degree. But the data from the Current Population Survey that Livingston used didn’t have measure of school attendance for people over age 25 until 2013. So I used the 1990 decennial Census and the 2013 ACS, which both have a measure of school attendance. Unfortunately, the 1990 Census doesn’t identify births, so I counted women as having had a birth if they were living in their own (or their husbands’) households with an “own child” age 0, which is not bad.
I took all the women ages 20-44 who already had a BA degree or higher, were attending school, and were living in their own (or their husbands’) households. In 1990 this was 3.4% of all women in that age group, and by 2013 it was 4.7% — a much bigger group. In 1990 3.5% of them had an infant, but that had increased to 4.6% by 2013. This is consistent with the Livingston finding that they are going to get advanced degrees and reach age 40-44 with more kids (if they experienced this birth rate difference every year, the completed fertility rates would be much higher for the later cohort).
Here are the breakdowns of the two cohorts according to the risk factors for childbearing I just described:
Notice: There are more in their prime childbearing ages (25-34), fewer married, and more Black and Hispanic. As it turns out, a regression analysis shows that the age change accounts for about a quarter of the increase in childbearing, while the change in marital status goes the other way about 8%, meaning they would have had even more kids if more were married. The race/ethnic effects are very small.
That also means the increase in fertility is not just compositional, the result of demographic changes. There is still an increasing tendency to have a child in this group, holding constant these factors. Adjusting for marital status and race/ethnicity, here are the predicted probabilities of having a birth in 1990 and 2013, by age:
Although the younger average age is a big factor, then, there is also a higher chance of having a birth at every age for college graduates pursuing advanced degrees. Why?
The optimistic interpretation of rising fertility for women with advanced degrees is that the cultural and organizational context has changed the childbearing calculus. The husbands or partners of these women are more supportive now. And their workplaces — or the workplaces they anticipate entering — have grown more accepting of professional women with children. Some schools have childcare and lactation spaces for graduate students. So having children may seem more reasonable. It’s also possible — and this is not contradictory — that the growth of this group has been driven by those who are less narrowly focused on their careers. To be a woman pursuing an advanced degree in 1990 you had to be a little more of a pioneer than you do now, so that path may have attracted a different group of women.
On the other hand, this is consistent with an inequality story: that those with better jobs and economic security, and family stability, have a growing advantage when it comes to raising children. Looking forward, I worry that the logistics of successful parenting are becoming an insurmountable challenge for too many people who don’t have enough control over their work lives. If we don’t improve the situation with healthcare, childcare, and family leave, then we risk increasingly making children a luxury that fewer families believe they can afford.
We are trying to fit our rapidly evolving social lives within the relatively narrow biological limits of human reproduction. The inconvenient truth is that the biological prime years for reproduction are also essential years for developing our human capital and adult relationships. We need collective efforts in the form of social policy to manage this compression.