NewsWire: 6/01/21
- A new analysis argues that declining U.S. fertility rates are here to stay. A look at successive birth cohorts over the past 30 years indicates that women are having fewer children at every age studied. (Brookings Institution)
- NH: As many of you NW readers know, the total fertility rate (TFR) is defined as the answer to a rather abstract and counter-factual question: If a woman were to live her entire life in one year and give birth at every age at the same rate-by-age as all women in that year, then how many children would she have over her lifetime?
- Demographers prefer the TFR over the crude birth rate (births per women age 16-45) because it isn't biased by the age distribution of women in any given year. It's a neutral measure of behavior.
- But the TFR does share one drawback with the crude birth rate. It doesn't adjust for changes in the timing of births. For example, if women who haven't yet had children decided going forward that they would all start having the same number of children, but have them one year earlier in life, then every measure of births would surge in that one transition year. On the other hand, if they decided they would all start having children one year later, well, we would have a lot fewer births in that year.
- This timing or "tempo" effect is very relevant to the current debate over whether the US TFR will start rising again. Some optimists tell us not to worry about the recent TFR decline because it's just a sign that women are choosing to have babies later in life. It's a temporary thing. Once women reach their new and older birthing norm, the TFR will rise back to where it was before.
- But there's a problem with this argument. It only makes sense if you're starting from a very young age of first birth and you're only talking about a few years of suppressed TFR. But in the US we started from a mean age of first birth at over age 25 in 2008, and since then the TFR has been declining for nearly 12 straight years. (In 2021, it will certainly decline again for the 13th year.) That's a lot of "tempo" to recover from!
- If the tempo effect were operative, despite the falling TFR, one telltale sign should be a substantial rise in the birthrate of 30-34 year-olds. At some point, women born in the late-1980s will need to "catch up" on births--and if that doesn't happen in the 30-34 age bracket, it's biologically unlikely to happen for these cohorts later in life. But through the year 2019 we haven't yet seen any such rise. (See chart 6 in my presentation, "2020 Demography Review: United States.") And according to the CDC's just-released provisional data, this rate went down again by -3.6% in 2020.
- Melissa S. Kearney and Phillip Levine of the Brookings Institution apparently agree with me. But they have a more elegant and visually persuasive way to make the point.
- They begin by showing the age-specific fertility rate of each birth cohort of women, starting with those born in 1975 and moving forward at 5-year intervals to the year 2000. Here's what it looks like.
- You don't see a lot of catching up going on, do you? To make the point more clearly, the authors track each cohort by children ever born.
- Here we can see that if there is a cohort that seems to have played catch-up successfully, that would be late-wave Xer women (born in 1975). They have had 2.2 children, which is actually a bit higher than any TFR over their lifetime--evidence that, yes, they did get an edge later in life by raising the early-30s birthrate back in the early 2000s. But it doesn't look like the next cohort will catch them. In fact, it doesn't look like any of the later cohorts will catch up with any of the cohorts born before them.
- Finally, the authors do a thought experiment. They run three scenarios for all the younger cohorts. In the first "conservative" scenario, the younger cohorts will in the future give birth at rates that rise and fall in the same relative pattern as the 1975 and 1980 cohorts. In the second "moderate" scenario, their birth rates will speed up and match the earlier cohorts' birth rates from age 30 on. And in the third "aggressive" scenario, their birthrates will exceed the birth rates of the earlier cohorts by +10% at age 30 and stay +10% higher for the rest of their lives.
- Here's an example of what that looks like for the 1995 cohort.
- The results? In every scenario, later-born cohorts of mothers will fall short of the late-wave Xers' benchmark. And in every scenario, cohorts born after 1985 will fall short of the 2.1 replacement rate.
- As the authors correctly point out, this low-fertility outlook has very little to do with the pandemic. The cumulative trends were all in place long before Covid-19 erupted. But of course the pandemic will push more Millennial women toward an even lower lifetime birth trajectory. That won't just put them on course to have fewer kids than older moms did, but also to have a lot fewer kids than what they regard as their "ideal family size" (as measured by just about every survey).
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