The Decline in Latter-day Saint Fertility Over the Past Decade

While members of the Church are known for our large families, anecdotally it has seemed that Latter-day Saint childbearing has been cratering and that we’ve been losing a lot of our fertility advantage. The problem is, getting robust, current childbearing metrics requires a fairly large sample size because it requires capturing enough women who have had a child in the past year to get reliable numbers, and surveys that ask about religion aren’t even close to being large enough.

So here I use Census Bureau data. Specifically, I’m assuming that if Latter-day Saint fertility (quick aside, for non-medical demography “fertility” means childbearing, not the ability to bear children) has been catering we’d see it in the numbers of Utah County and Madison County, Idaho (the county where BYU-Idaho is). Here I look at changes in the Total Fertility Rate. Without going into too much of the math, the TFR is the number of children across her lifetime a woman would have if she was exposed to all of the age-specific childbearing rates of that given year. In other words, if she lived her entire life in a setting like the year 2021, that’s how many children she would have. Here I use the ACS 5-year estimates for 2021, 2016, and 2011 for TFR. (My calculated US TFR is just a hair above the published estimates. I’m not sure, but I suspect that this is because I’m including the 45-50 age bracket when some TFR calculations count up until 45, or maybe our cutoff dates are different).

As seen, in the past ten years there has indeed been a decline in childbearing, but it looks comparable to the decline in the US more broadly. Madison County appeared to have stalled for a five-year period, but the sample size is small enough population-wise that there’s probably some noise involved there. Surprisingly to me given stereotypes about BYU-Idaho students, Madison County actually has a lower fertility rate than Utah county, although I don’t know how much of Madison County is BYU-Idaho.

So my conjecture was wrong. Latter-day Saint fertility probably hasn’t been declining much faster than US fertility in general. (This is especially true if some of the decline in Utah County’s fertility is due to a decrease in the percent Latter-day Saint.) We’re essentially following national trends.

5 comments for “The Decline in Latter-day Saint Fertility Over the Past Decade

  1. Stephen, for the differential in fertility rates, would any of the following affect your analysis?

    The BYU-Idaho student population (roughly 20,000) is a much larger share of the Madison County population (52,000), so what students do in Idaho affects the statistics a lot more in Utah County (population 665,000).

    BYU offers graduate and professional programs that keep students in the area farther into their child-bearing years. Also, Utah County is part of a much larger metropolitan area, so there are better chances of starting a career there, while fewer BYU-Idaho students are staying in the area after graduation.

    So Utah County probably has a more typical population profile, while Madison County might have less representation for the ages 25+, which are prime child bearing years.

    But I don’t know if any of this would affect your analysis.

  2. The age effect of being in childbearing years is taken into account in the TFR, but people do tend to drift to certain areas in order to have children and that does affect things. For example, I played around with city-specific TFRs and Provo was lower than I thought it would be (although I don’t remember the number off the top of my head), whereas Eagle Mountain had a TFR of around 4, which is super high but makes sense: 30-year olds move to relatively affordable Eagle Mountain to have babies and raise families, 30-year olds move to more expensive Provo to get an education or (increasingly) to develop a career. Your sense about BYU-Idaho is probably right. There are a few brave BYU-Idaho students bold enough to have families at that stage given their expected salaries at that level, but for the most part I assume most are waiting until they move to some Eagle Mountain-type suburb to raise their kids.

  3. I think the comments have hit on a key factor. I’m the oldest of eight kids, and my Mom had me when she was 21. If 25+ are now the prime child-bearing years or people now move at 30 to have babies, you’re not going to get families with eight kids.

    When I was young, I remember hearing frequently that we should not delay marriage or having children. We were told that, yes, we’d be poor at first, but it would all work out. (Most of the people saying that had survived the Depression, so compared to what they experienced we wouldn’t be all that poor anyway.) As I’ve said before, I don’t recall hearing that message recently. Maybe I’ve missed it–please correct me if I’m wrong. Young people today are certainly told that marriage and children are important, but I don’t think there’s much discussion of timing. Economics is certainly a factor in that–Stephen C is right that you have to be brave to have children in your early 20s given the modern economy.

    That raises all sorts of fascinating questions about the role of fertility in our theology. I remember being told all sorts of reasons why having as many children as you could was the righteous thing to do. If you go back in our history you can find support for going all out “quiverfull.” But if young people today go by what they’re being told by Church leaders today, they may well conclude that having two kids in your early 30s is perfectly fine. And I’m not going to tell them they’re wrong! (Of course, there’s personal revelation as well: when my parents got married they planned to have two children, but they were obedient when the Spirit prompted them to have one more. Repeatedly.)

  4. @ RLD: Pronatalist rhetoric was much, much bigger deal (, because life and situations are more complicated now than they were when we all lived in villages and you had the choice of four potential partners I suspect the Church doesn’t want to get more involved in mommy-wars types debates than they have to, but as a result we’ve seen very little rhetoric explicitly celebrating large families, which I think is an overcorrection.

  5. One of my daughters is adamant that she will never have kids, although she’s a teenager so she may change her mind.

    When asked why she feels so strongly about it, she replies that she saw how miserable raising kids was for me. And she’s right, especially when I was dealing with babies. Depression, exhaustion, loneliness… SAHMhood left me deeply unhappy for years. My daughter was a firsthand witness to my experience. Why would she want to live like that?

    She sees all of the YW lessons on the beauty of motherhood as disingenuous because they skip over the misery part (although I understand some women don’t go through the misery, lucky them).

    While I don’t regret my kids, I’m straight-out encouraging them to go for smaller families themselves. Then again, not too small as siblings are one of the greatest gifts a parent can give a kid (or at least in our family).

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