Births to 40-year-olds are less common but a greater share than in 1960

Never before have such a high proportion of all births been to women over 40 — they are now 2.8% of all births in the US. And yet a 40-year-old woman today is one-third less likely to have a baby than she was in 1947.

From 1960 to 1980, birth rates to women over 40* fell, as the Baby Boom ended and people were having fewer children by stopping earlier. Since 1980 birth rates to women over 40 have almost tripled as people started “starting” their families at later ages, but they’re still lower than they were back when total fertility was much higher.

Sources: Birth rates 1940-1969, 1970-2010, 2011, 2012-2013, 2014-2015; 2016; Percent of births 1960-1980, 1980-2008.

Put another way, a child born to a mother over 40 before 1965 was very likely the youngest of several (or many) siblings. Today they are probably the youngest of 2 or an only child. A crude way to show this is to use the Current Population Survey to look at how many children are present in the households of women ages 40-49 who have a child age 0 (the survey doesn’t record births as events, but the presence of a child age 0 is pretty close). Here is that trend:

In the 1970s about 60 percent of children age 0 had three or more siblings present, and only 1 in 20 was an only child. Now more than a quarter are the only child present and another 30 percent only have one sibling present. (Note this doesn’t show however many siblings no longer live in the household, and I don’t know how that might have changed over the years).

This updates an old post that focused on the health consequences of births to older parents. The point from that post remains: there are fewer children (per woman) being born to 40-plus mothers today than there were in the past, it just looks like there are more because they’re a larger share of all children.

* Note in demography terms, “over 40” means older than “exact age” 40, so it includes people from the moment they turn 40.

Fertility trends and the myth of Millennials

The other day I showed trends in employment and marriage rates, and made the argument that the generational term “Millennial” and others are not useful: they are imposed before analyzing data and then trends are shoe-horned into the categories. When you look closely you see that the delineation of “generations” is arbitrary and usually wrong.

Here’s another example: fertility patterns. By the definition of “Millennial” used by Pew and others, the generation is supposed to have begun with those born after 1980. When you look at birth rates, however,  you see a dramatic disruption within that group, possibly triggered by the timing of the 2009 recession in their formative years.

I do this by using the American Community Survey, conducted annually from 2001 to 2015, which asks women if they have had a birth in the previous year. The samples are very large, with all the data points shown including at least 8,000 women and most including more than 60,000.

The figure below shows the birth rates by age for women across six five-year birth cohorts. The dots on each line mark the age at which the midpoint of each cohort reached 2009. The oldest three groups are supposed to be “Generation X.” The three youngest groups shown in yellow, blue, and green — those born 1980-84, 1985-89, and 1990-94 — are all Millennials according to the common myth. But look how their experience differs!

Most of the fertility effect on the recession was felt at young ages, as women postponed births. The oldest Millennial group was in their late twenties when the recession hit, and it appears their fertility was not dramatically affected. The 1985-89 group clearly took a big hit before rebounding. And the youngest group started their childbearing years under the burden of the economic crisis, and if that curve at 25 holds they will not recover. Within this arbitrarily-constructed “generation” is a great divergence of experience driven by the timing of the great recession within their early childbearing years.

You could collapse these these six arbitrary birth cohorts into two arbitrary “generations,” and you would see some of the difference I describe. I did that for you in the next figure, which is made from the same data. And you could make up some story about the character and personality of Millennials versus previous generations to fit that data, but you would be losing a lot of information to do that.

Of course, any categories reduce information — even single years of age — so that’s OK. The problem is when you treat the boundaries between categories as meaningful before you look at the data — in the absence of evidence that they are real with regard to the question at hand.

Weathering and delayed births, get your norms off my body edition

You can skip down to the new data and analysis — or go straight to my new working paper — if you don’t need the preamble diatribe.

I have complained recently about the edict from above that poor (implying Black) women should delay their births until they are “financially ready” — especially in light of the evidence on their odds of marriage during the childbearing years. And then we saw what seemed like a friendly suggestion that poor women use more birth control lead to some nut on Fox News telling Rebecca Vallas, who spoke up for raising the minimum wage:

A family of three is not supposed to be living on the minimum wage. If you’re making minimum wage you shouldn’t be having children and trying to raise a family on it.

As if minimum wage is just a phase poor people can expect to pass through only briefly, on their way to middle class stability — provided they don’t piss it away by having children they can’t “afford.” This was a wonderful illustration of the point Arline Geronimus makes in this excellent (paywalled) paper from 2003, aptly titled, “Damned if you do: culture, identity, privilege, and teenage childbearing in the United States.” Geronimus has been pointing out for several decades that Black women face increased health risks and other problems when they delay their childbearing, even as White women have the best health outcomes when they delay theirs. This has been termed “the weathering hypothesis.” In that 2003 paper, she explores the cultural dynamic of dominance and subordination that this debate over birth timing entails. Here’s a free passage (where dominant is White and marginal is Black):

In sum, a danger of social inequality is that dominant groups will be motivated to promote their own cultural goals, at least in part, by holding aspects of the behavior of specific marginal groups in public contempt. This is especially true when this behavior is viewed as antithetical or threatening to social control messages aimed at the youth in the dominant group. An acknowledgment that teen childbearing might have benefits for some groups undermines social control messages intended to convince dominant group youth to postpone childbearing by extolling the absolute hazards of early fertility. Moreover, to acknowledge cultural variability in the costs and consequences of early childbearing requires public admission of structural inequality and the benefits members of dominant groups derive from socially excluding others. One cannot explain why the benefits of early childbearing may outweigh the costs for many African Americans without noting that African American youth do not enjoy the same access to advanced education or career security enjoyed by most Americans; that their parents are compelled to be more focused on imperatives of survival and subsistence than on encouraging their children to engage in extended and expensive preparation for the competitive labor market; indeed, that African Americans cannot even take their health or longevity for granted through middle age (Geronimus, 1994; Geronimus et al., 2001). And one cannot explain why these social and health inequalities exist without recognizing that structural barriers to full participation in American society impede the success of marginalized groups (Dressler, 1995; Geronimus, 2000; James, 1994). To acknowledge these circumstances would be to contradict the broader societal ethic that denies the existence of social inequality and is conflicted about cultural diversity. And it would undermine the ability the dominant group currently enjoys to interpret their privilege as earned, the just reward for their exercise of personal responsibility.

But the failure to acknowledge these circumstances results in a disastrous misunderstanding. As a society, we have become caught in an endless loop that rationalizes, perhaps guarantees, the continued marginalization of urban African Americans. In the case at hand, by misunderstanding the motivation, context, and outcomes of early childbearing among African Americans, and by implementing social welfare and public health policies that follow from this misunderstanding, the dominant European American culture reinforces material hardship for and stigmatization of African Americans. Faced with these hardships, early fertility timing will continue to be adaptive practice for African Americans. And, reliably, these fertility and related family “behaviors” will again be unfairly derided as antisocial. And so on.

Whoever said demography isn’t theoretical and political?

A simple illustration

In Geronimus’s classic weathering work, she documented disparities in healthy life expectancy, which is the expectation of healthy, or disability-free, years of life ahead. When a poor 18-year-old Black woman considers whether or not to have a child, she might take into account her expectation of healthy life expectancy — how long can she count on remaining healthy and active? — as well as, and this is crucial, that of her 40-year-old mother, who is expected to help out with the child-rearing (they’re poor, remember). Here’s a simple illustration: the percentage of Black and White mothers (women living in their own households, with their own children) who have a work-limiting disability, by age and education:

Not too many disabilities at age 20, but race and class kick in hard over these parenting years, till by their 50s one-in-five Black mothers with high school education or less has a disability, compared with one-in-twenty White mothers who’ve gone on to more education. That looming health trajectory is enough — Geronimus reasonably argues — to affect women’s decisions on whether or not to have a child (or go through with an accidental pregnancy). But for the group (say, Whites who aren’t that poor) who have a reasonable chance of getting higher education, and making it through their intensive parenting years disability-free, the economic consequence of an early birth weighs much more heavily.

Some new analysis

As I was thinking about all this the other day, I went to check on the latest infant mortality statistics, since that’s where Geronimus started this thread — with the observation that White women’s chance of a baby dying decline with age, while Black women’s don’t. And I noticed there is a new Period Linked Birth-Infant Death Data File for 2013. This is a giant database of all the births — with information from their birth certificates — linked to all the infant deaths from the same year. These records have been used for analyzing infant mortality dozens of times, including in pursuit of the weathering hypothesis, but I didn’t see any new analyses of the 2013 files, except the basic report the National Center for Health Statistics put out. The outcome is now a working paper at the Maryland Population Research Center.

The gist of the result is, to me, kind of shocking. Once you control for some basic health, birth, and socioeconomic conditions (plurality, parity, prenatal care, education, health insurance type, and smoking during pregnancy), the risk of infant mortality for Black mothers increases linearly with age: the longer they wait, the greater the risk. For White women the risk follows the familiar (and culturally lionized) U-shape, with the lowest risk in the early 30s. Mexican women (the largest Hispanic group I could include) are somewhere in between, with a sharp rise in risk at older ages, but no real advantage to waiting from 18 to 30.

I’ll show you (and these rates will differ a little from official rates for various technical reasons). First, the unadjusted infant mortality rates by maternal age:

Infant Death Rates, by Maternal Age: White, Black, and Mexican Mothers, U.S., 2013. Infant death rates per 1,000 live births for non-Hispanic white (N = 1,925,847), non-Hispanic black (N = 533,341), and Mexican origin (N = 501,390) mothers. Data source: 2013 Period Linked Birth/Infant Death Public Use File, Centers for Disease Control.

These raw rates show the big health benefit to delay for White women, a smaller benefit for Mexican mothers, and no benefit for Black mothers. But when you control for those factors I mentioned, the infant mortality rates for young Black and Mexican mothers are lower — those are the mothers with low education and bad health care. Controlling for those things sort of simulates the decisions women face: given these things about me, what is the health effect of delay? (Of course, delaying could contribute to improving things, which is also part of the calculus.) Here are the adjusted age patterns:

Adjusted Probability of Infant Death, by Maternal Age: White, Black, and Mexican Mothers, U.S., 2013. Predicted probabilities of infant death generated by Stata margins command, adjusted for plurality, birth order, maternal education, prenatal care, payment source, and cigarette smoking during pregnancy; models estimated separately for white (A), black (B), and Mexican (C) mothers (see Tab. 1). Error bars are 95% confidence intervals. (A separate test showed the linear trend for Black women is statistically significant.) Data source: 2013 Period Linked Birth/Infant Death Public Use File, Centers for Disease Control.

My jaw kind of dropped. Infant mortality is mostly a measure of mothers’ health. Early childbearing looks a lot crazier for White women than for Black and Mexican women, and you can see why the messaging around delaying till your “ready” seems so out of tune to the less privileged (and that really means race more than class, in this case). Why wait? If women knew they had higher education, a good job, and decent health care awaiting them throughout their childbearing years, I think the decision tree would look a lot different.

Of course, I have often said that delayed marriage is good for women. And delayed childbearing would be — should be — too, as long as it doesn’t put the health of the mother and her children at risk (and squander the healthy rearing years of their grandparents).

Please check out the working paper for more background and references, and details about my analysis.

Colorado leads drop in teen birth rate, 2008-2013

Yesterday I tweeted a figure of teen birth rate changes based on the fertility question in the American Community Survey. It showed Colorado with an above-average drop in teem births from 2008 to 2013, but not the biggest drop in the country. I have a better chart on this below.

The reason for the attention was this story in the New York Times, which reported:

Over the past six years, Colorado has conducted one of the largest experiments with long-acting birth control. If teenagers and poor women were offered free intrauterine devices and implants that prevent pregnancy for years, state officials asked, would those women choose them?

They did in a big way, and the results were startling. The birthrate among teenagers across the state plunged by 40 percent from 2009 to 2013, while their rate of abortions fell by 42 percent, according to the Colorado Department of Public Health and Environment.

Since the article didn’t provide data for comparisons, and I knew teen births were declining all over, I wanted to see if Colorado’s experiment was really such a standout. The figure was republished by German Lopez at Vox.com in a post on the Colorado program. Although the figure showed Colorado with a big drop, it still cast doubt on the program because it showed four states and DC with bigger drops.

I’m retracting that figure today, because I realized — and I should have known this — that we have teen birth rates by state and year from the vital records data reported by the National Center for Health Statistics. In these reports we can see that Colorado did, in fact, have the largest decline in teen births from 2008 and 2013 (their program started in 2009). Here’s the new figure:

The story isn’t that different between NCHS and ACS data, but Colorado is trying to raise money to continue the program, and it sure is nice for them to have this comparison. It’s great to have data right away — and share it — and it’s also great, even greater, to have better data. The vital records data is more complete and reliable, since it is not based on a sample, and teen births are rare enough now that sampling variation matters, even in a big sample like the ACS. So I regret that I published the earlier figure.

That said…

The teen birth rate is declining all over the country, even in places with terrible policies, so the Colorado program — valuable as it may be — is swimming with the tide.

The reason teen births are declining all over is because the teen birth rate is a myth — what’s really happening is women in the U.S. are having their children later, for economic and social reasons that go way beyond what’s happening with teens per se. I have written about this a few times:

• Marriage promotion and the myth of teen pregnancy
• US teen birth rates remain high, and they’re not falling for the reasons you’ve heard

See also:

• Why are women with advanced degrees having more children?

The total fertility rate, with instructions, in 9 minutes

Maybe because I haven’t had a classroom full of students since December, I made an instructional video.

In 9 minutes I explain what the total fertility rate is and then illustrate how to get the data you need to calculate it using IPUMS’s American Community Survey analysis tool. In the dramatic last five minutes we calculate the TFR for the United States in 2013, and match the official number. Wow. And you thought your holiday weekend was going to be fun already.

I want more people to have a hands-on feel for basic demography, and to realize how easy it is, and how accessible, with the tools we have nowadays. So, this is for students, non-demographic researchers, and journalists.

The video:

And here’s the end product (a little touched up):

Check it out if you’re having trouble sleeping.

More fathers married when their first child is born? Probably not

A startling data brief from the National Center for Health Statistics reports that the percentage of fathers who weren’t married at the time of their first births fell from the 1980s to the 2000s. Here is the first “key finding”: “The percentage of fathers aged 15–44 whose first births were nonmarital was lower in the 2000s (36%) than in the previous 2 decades.”

That is shocking. How could we have a falling percentage of fathers not married at the time of their first births? The author, Gladys Martinez, writes:

Results from this study indicate that in the 2000s, the percentage of fathers with nonmarital first births declined. However, the percentage of fathers whose nonmarital first births occurred within a cohabiting union increased. This pattern differs from that for the mother. Data for women showed that the share of all births that occurred to unmarried women has doubled between 1988 and 2009–2013, and that the increase was driven by an increase in the share of births to cohabiting women.

Here is the main figure, showing the decline in nonmarital first births for fathers:

But I think this is not correct (this concern was first raised to me by Pew researcher Gretchen Livingston). Here’s why. As the figure shows, the source for these three decades of data is the National Survey of Family Growth. The earliest this survey captured men’s births (awkward phrase, but you know what I mean) was in 2002. And the ages included in the survey were 15-44. But the figure has information about births in the years 1980-1989. By my math, the oldest a 15-44-year-old in 2002 could have been in 1989 is 31. So that 2002 survey is only returning data on the marital status of men ages 15-31 in the 1980s.

I always have to do one of these to make sure I’m not crazy when I’m trying to work something like this out. This is how old 15-44 year-olds in 2002 were in the 1980s, excluding those under 15 (click to enlarge):

They’re all 15-31 (or younger) in the 1980s. In contrast, if they combine the 2006-2010 survey (collected over 5 years) with the 2011-2013 survey (collected over 3 years), they have men ages 15-42 in the 1990s and 15-44 in the 2000s. So, as the age of the men in the sample rose, the proportion married when they had their first birth rose, too. This is what we would expect: younger first-time parents are much less likely to be married.

Consider, then, the followup finding from the brief: for men of every age the proportion unmarried at the time of their first birth has increased:

How can it be that the overall proportion unmarried is falling, while it’s rising for each age group? The answer in the data brief is that first-time unmarried fathers are getting older. But remember — the samples are getting older across these decades, because of the timing of the surveys: they age from 15-31 to 15-44. That explains the next figure perfectly. Look at that increase in the proportion of unmarried first-time fathers who are 25-44:

In the 1980s, just 8% of first-time unmarried fathers were age 25-44, compared with a whopping 33% in the 2000s. But doesn’t it seem likely that you’ll have fewer men ages 25-44 in a group that only goes up to age 31, versus a group that goes all the way up to age 44?

This stuff gets confusing, but I’m pretty sure this is right. That is, wrong. I do not believe that there is a falling percentage of fathers having first births when they’re not married. What looked like a weird, complicated demographic problem — falling unmarried first-fatherhood along with rising unmarried first-motherhood — is probably an artifact of a weird, complicated problem in the analysis.

There is nothing in the data brief to suggest there was an adjustment for the changing age composition of the data for these decades, but maybe they did something I don’t understand. If not, I think NCHS should correct or retract this report.

Updated age education birth figures

As fertility continues in the news (see last week’s post on rising birth rates for women with higher education), I am preparing for a planned appearance today on the Kojo Nnamdi Show, on the “grandparent deficit” associated with births at advanced parental age. So I updated some old figures I made in 2012.

These come from two posts:

• Poverty Poses a Bigger Risk to Pregnancy Than Age, which argued that a focus on parental age was distracting us from economic inequality. I concluded: When it comes to parents’ age versus social class, the challenges are not either/or. We should be concerned about both. But addressing the health problems of parents—especially mothers—with less than a college degree and below-average incomes is the more pressing issue—both for potential lives saved or improved and for social equality.
• Births to mothers in their forties are less common now than in the old days, which explained that, although first births at older ages are more common, the birth rate among older women is lower now than it was during the Baby Boom. That is, women aren’t more likely to have a kid at age 40 now — they’re just more likely to have their first at that age.

Here are three figures I’ve updated.

The first shows the distribution of births by education within each age group of mothers. It shows, for example, 85% of women under 20 who had a birth in 2013 had a high school education or less. The highest levels of education are found among women have babies in their late 30s (note these are not just first births):

The next one shows the same information, but now arranged as percentages of all births. This shows, for example, that 27% of all births are to women in their late 20s, with the majority of those having some college education or less:

Finally, the odd phenomenon in which, although the percentage of all births to women age 40+ has increased to the point that it surpassed the Baby Boom years, the birth rate for women that age is still much lower than it was:

So the average 40-year-old was more likely to have a baby in 1960 than today (15.5 per 1000 versus 10.5 per 1000), but a baby born today is more likely to have a mother 40 or older (2.3% versus 2.8%). That’s because more people were having births at all ages in 1960. The U-shape here reflects two historical trends: first, the total number of children per woman declined, which meant fewer born at older ages because people stopped earlier. Then, as marriage age increased, along with women’s education, women started delaying their first births, which led to increasing birth rates — and proportions of births — at older ages.

Sources:

The source for the first two figures is my analysis of 2013 ACS data from IPUMS.org. The last one is from National Center for Health Statistics reports: here, here, here, and here; as well as a couple of old Statistical Abstracts, here and here.