by Steven Camarota
Like all other First World countries, the United States is experiencing a significant decline in fertility. President Trump has suggested paying Americans to increase the nation’s fertility rate. He is right to be concerned. Low fertility and increasing life expectancy are the two primary drivers of population aging. Some have argued that because immigrants tend to have more children, immigration can fix this problem. But the latest fertility data show that immigration has at most a small impact on birth rates.
Immigration does add significantly to the number of births. In 2023, about one in five births in the United States was to an immigrant mother. What matters for population aging, however, is birth rates.
One of the easiest ways to measure the impact of immigration on the nation’s birth rates is to use the annual American Community Survey (ACS), collected by the Census Bureau. The immigrants (or foreign-born) in the data include everyone who is not a U.S. citizen at birth — naturalized citizens, lawful permanent residents, long-term temporary visitors such as guest workers and foreign students, and illegal immigrants. The Census Bureau is clear that illegal immigrants are included in the data, although some share are missed. The survey asks all women ages 15 to 50 if they’ve had a child in the last year.
With the ACS we can calculate a total fertility rate (TFR), which represents the number of children a woman can be expected to have in her lifetime if present trends continue. As a general rule, a TFR of at 2.1 is “replacement level” – the minimum necessary to maintain the current population in the long run — putting aside people entering or leaving a country.
By 2023 the TFR of immigrant women was 2.187 children, slightly above replacement level. For native-born women it was 1.726. The overall U.S. fertility rate (immigrants and the native-born together) was 1.804. Notice that, although the immigrants do have a higher TFR, their presence raised the nation’s overall TFR in 2023 by a little less than .08 children (1.726 subtracted from 1.804). That increase amounts to 4.5 percent. That’s it.
There are other ways to calculate fertility. The simplest way is by dividing the number of births by the total number of people, not just women of reproductive age. This is sometimes referred to as the general fertility rate (GFR). Immigrants do have a slightly larger impact on the GFR than TFR because not only do immigrant women in their reproductive years have somewhat higher fertility, but immigrants are also somewhat more likely to be ages 15 to 50. But again, the impact is small. In 2023, the GFR for the whole U.S. population was 11.9 births per thousand with immigrants, and 11.2 without them — a 6.6 percent increase. The overall impact on fertility is still small.
The reason the effect on GFR is small is not just that immigrant fertility is not that much higher. It is also that immigration adds to the entire population, so a very large share of immigrants are not women in their childbearing years. To illustrate, in 2023 immigrants were about 16.4 percent of all women ages 15 to 50, but they were also about 15 percent of all people 65 and older. Many immigrants do arrive young, but they age over time like everyone else. Immigrants do not stay young, and they do not have huge families the way some immigration enthusiasts seem to imagine.
Many factors explain the decline in the fertility in the U.S. These include uncertainty about the future, changing expectations about careers and roles of women, the cost of housing, the steady decline in marriage, and the falloff in religious belief. One of the more interesting recent findings is that immigration may be reducing the fertility of the U.S.-born.
My analysis with colleague Karen Zeigler shows that in the largest metro areas in the United States, increased immigration is correlated with a decline in the fertility of the U.S.-born. A 2018 study of the 1980 Mariel boatlift to Miami found that the increase in Cuban immigrants in the city significantly reduced the fertility of the U.S.-born in the short term. The primary impact was on women who lived in rental housing. This suggests that immigration reduces fertility in receiving communities by making it more difficult for younger, less affluent couples to move into larger or owner-occupied housing.
In addition, a recent working paper by David Solomon found that as ethnic diversity increases in an area, the number of children born to residents decreases. The relationship holds across many places and time periods. Solomon suggests one possible explanation for this is “homophily” — the tendency for people from similar backgrounds to associate with each other. The extent to which diversity makes it harder to find a marriage partner of the same ethnicity could be a reason why diversity reduces fertility. My colleague Jason Richwine recently calculated the increase in diversity caused by immigration could be enough to entirely offset the small positive impact that immigrants have on the overall TFR.
Demographers have long known that immigration is no fix for low fertility rates or population aging more generally. Immigrants grow old over time and their fertility is not that much higher than the native-born. This means that by the time the U.S.-born children of immigrants join the labor force, a significant share of their immigrant parents will be at or near retirement age, thus adding to the number of both workers and retirees.
We can see this by looking at the latest population projections from the U.S. Census Bureau. In the “high-immigration” scenario they assume net immigration will total 59 million by 2060 and 59 percent of the population will be working age (18 to 64) in that year. The bureau’s “low immigration” scenario assumes net immigration of just 18 million over this time period and finds 58 percent will be of working-age.
It is true that in the high immigration scenario U.S. population is much larger in 2060. But varying the level of immigration adds to the whole population, not just the working-age. It is not at all clear that making the population larger improves our quality of life. Making the country more densely settled likely reduces housing affordability and increases traffic and congestion to say nothing of the environmental impact.
When thinking about low fertility, it is important to note that America is by no means alone in facing this issue. In fact, almost all of the top immigrant-sending countries now have below replacement level fertility, including Mexico, China, India, and El Salvador. We are going to have to adjust to this new reality or figure out ways to encourage American couples to have more children. But whatever we decide, we need to recognize that immigration can do very little to address this issue.
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Steven Camarota is the Director of Research at the Center for Immigration Studies.
One of the major reasons for the fertility rate (who came up with that phrase?) is that Americans have been raising a few generations of narcistic children. They do not have children because it might impede their precious self-indulgence. There is no substitute for the pride one gets by watching a child grow up. They are really missing the boat on this one.