Here’s a demographic oddity for ya’

Here’s a demographic oddity for ya’

from https://www.flickr.com/photos/92334668@N07/11368402995

In the news last week:  “The U.S. fertility rate just hit a historic low. Why some demographers are freaking out.

The United States is in the midst of what some worry is a baby crisis. The number of women giving birth has been declining for years and just hit a historic low. If the trend continues — and experts disagree on whether it will — the country could face economic and cultural turmoil.

According to provisional 2016 population data released by the Centers for Disease Control and Prevention on Friday, the number of births fell 1 percent from a year earlier, bringing the general fertility rate to 62.0 births per 1,000 women ages 15 to 44. The trend is being driven by a decline in birthrates for teens and 20-somethings. The birthrate for women in their 30s and 40s increased — but not enough to make up for the lower numbers in their younger peers.

Whether the low teen and 20-something birthrates are due to an increase in the use of highly-effective contraceptive methods, a decrease in the frequency with which they’re having sex, or a more general increase in the motivation to avoid pregnancy, or, rather, exactly how all of these factors play into this development, isn’t clear.  And, to the best of my understanding, this decrease in the birth rates for these younger groups is a new enough trend that we don’t know whether, in the coming decade, we’ll see that these women merely postponed childbirth, or are, on average, having fewer children over their lifetime.  (Note that the underlying CDC report gives a TFR of 1.818, the lowest since 1984.)

But demographers confidently expect the fertility rates to rebound, and here’s something curious:  the WHO fertility rate projections likewise assume that, consistently, for countries with below-replacement fertility levels, those rates will increase, e.g.,

Japan’s current TFR is 1.48.  The WHO projects, in their “medium variant,” that it will increase progressively until it reaches 1.79 in 2100.

Korea’s TFR is projected to grow from 1.32 to 1.78.

Germany, from 1.47 to 1.73.

In North America, Canada is projected to move from 1.56 to 1.78.

Other countries which already have TFRs of slightly below 2 are presumed to stay at about that level, e.g., the US is projected to move from 1.89 to 1.92.

And, well, Sub-Saharan Africa as a whole is projected to move from 4.75 to 2.16.

Now, it’s not a surprise to me that demographers project that high-fertility countries will see decreases in fertility, or that countries that have been reasonably stable and replacement-ish will stay that way.  But I’m curious as to the basis for the assumption that the super-low fertility countries will “naturally” rebound.  Is the expectation that their levels of immigration will increase, and that those immigrants will be more fertile than the native population?  Is there a presumed equivalent to the so-called “Roe effect” — that is, an assumption that the lion’s share of childbearing will be done by larger families, and an increasing share of children will come from larger families and expect to have more than one child?  The WHO site has links to data but no real explanations.

Readers, what do you think?

 

Image from https://www.flickr.com/photos/92334668@N07/11368402995; creative commons license.


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