Left-Leaning Americans Driving U.S. Birth Decline, New Study Finds

A study in *Scientific Reports* by Martin Fieder of the University of Vienna and Susanne Huber analyzes General Social Survey data from 1970-2022. The authors find that left-leaning Americans have markedly lower fertility than conservatives, a pattern they argue drives the nation’s recent birth decline.

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Earlier work by the authors showed that political extremes often have higher fertility worldwide. Prior studies noted a U.S. conservative advantage emerging in the 1990s and that European conservatives have more children and grandchildren than liberals, suggesting a broader rightward demographic shift.

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The researchers analyzed 22,975 adults (10,681 men, 12,294 women) in 16 birth cohorts from 1903-1907 to 1978-1982. Political orientation, measured on a seven-point scale, was grouped into left, center, and right. Using a phenotypic-selection method, they found little orientation-fertility link in early cohorts, but from the 1943-1947 cohort onward, right-wing respondents maintained fertility at or above replacement (2.1 children per woman) while left-wing respondents fell well below; centrists stayed slightly below replacement. The gap is driven mainly by White Americans; among Black Americans, fertility declined overall but remained similar across politics. Higher education predicts fewer children, while frequent religious attendance predicts larger families, especially for men, though this effect weakened.

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The authors argue the fertility gap may gradually shift the U.S. electorate toward conservatism, echoing rightward trends. Demographic processes complement persuasion and electoral dynamics in shaping political composition.

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Fieder says “provides new insight into the demographic drivers of fertility decline” and that “political change is not driven only by persuasion, elections, or short-term social trends, but also by demographic processes.” He notes that contraception contributed to the left-wing fertility drop, though it cannot be directly tested.

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Being observational, the study cannot establish causality between political views and childbearing. It lacks data on fertility intentions or contraceptive use, and the left-right scale may oversimplify complex ideology.

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Black Americans show no comparable fertility divergence, and the study cannot verify the contraception hypothesis. Further research should address economic versus social conservatism and patterns in developing nations.

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• “We expected these results, but not to such a dramatic extent,” — Martin Fieder, Associate Professor of Evolutionary Demography, University of Vienna

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• “We found that the gap began with the introduction of modern contraception,” — Martin Fieder

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• “We hypothesize that differences in the use of modern contraceptives contributed to the dramatic decline in fertility among individuals left of the political center,” — Martin Fieder

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• “The main takeaway is that political change is not driven only by persuasion, elections, or short-term social trends, but also by demographic processes,” — Martin Fieder

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Fieder and Huber plan to test if similar fertility-politics links appear outside wealthy post-industrial nations, to distinguish economic from social conservatism, and to study modern contraception’s role in future demographic and political trends.

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