Volume 49 - Article 29 | Pages 769–782  

Ultra-Orthodox fertility and marriage in the United States: Evidence from the American Community Survey

By Lyman Stone

Response Letters

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02 February 2024 | Response Letter

Do Ultra-Orthodox Jews Exhibit Natural Fertility?

by Lyman Stone

The letter by Garenne responding to Stone (2023) raised essentially two novel points, for which the author is grateful; first, a theoretical comment about natural fertility; second, an empirical argument that Ultra-Orthodox Jewish fertility is in fact similar to fertility in non-contracepting, natural fertility societies (such as rural Niger 1982–2012). Garenne’s comment is appreciated. Due to space constraints in the Empirical Findings format, the original paper could not provide a full discussion of marital fertility; however, Garenne has independently replicated marital fertility estimates produced in the course of Stone (2023) but not published and which were referred to in the concluding discussion. A successful replication is always encouraging.

“Natural fertility” (meaning, fertility without evidence of parity-specific control within marriage, the usual definition since at least Henry XYZ) received only a single mention in Stone (2023), since data on parity-specific birth rates is not available in the ACS. Ultra-Orthodox Jewish fertility is indeed lower than most documented natural fertility populations as shown in Figure 1 below, however, the introduction of rural Niger as a possible natural fertility population with similar or lower fertility is an interesting exception I had not anticipated at the time of writing.

However, Stone (2023) did not comment on whether Ultra-Orthodox Jews were or were not a natural fertility population. Without data on parity-specific birth data, this cannot be conclusively assessed. Rather, Stone (2023) remarked on the exceptional fact that Ultra-Orthodox Jews did have “pretransitional” (i.e., very high) fertility rates alongside well-documented contraceptive usage, abortion access, and (not mentioned in the paper) documented numeric family size preferences in surveys (DellaPergola 2009) around 4 children per woman. This leads to one strong agreement with Garenne’s note: Ultra-Orthodox Jewish fertility is surprising, given its evident “modernity” in some quite salient respects. Whether these high fertility rates constitute “natural fertility” will necessarily depend on assessments of parity-specific stopping behavior, and in particular how Ultra-Orthodox Jewish women use contraception (spacing, stopping, etc.), questions Stone (2023) could not answer.

Finally, one caveat to Garenne’s comparison must be noted. Figure 1 in Garenne’s note excludes marital fertility at ages 15–19, yet births at very young ages can be a large part of fertility, especially if marriage ages are young, as they are in rural Niger and for Ultra-Orthodox Jews. Figure 1 below replicates marital fertility rates for Yiddish-speakers in the ACS as Garenne did, and compares them to rural women in Niger in the 1992 DHS wave (I did not have access to 1982 data as Garenne had, and given documented contraceptive usage in this population in 1998 and later waves, felt 1992 was the most appropriate available possibly natural fertility population). As can be seen, women in Niger had considerably higher fertility rates once births before age 20 are considered: marital fertility of 8.2 in total for Yiddish-speakers, vs. 8.9 for rural married women in Niger in 1992. The low birth rates of young married Ultra-Orthodox Jews are a remarkable feature of their demography, and point to at least the possibility fertility control within marriage at least for the youngest marriages.

Lyman Stone


DellaPergola, S. (2009). Actual, intended, and appropriate family size among Jews in Israel. Contemporary Jewry 29(2): 127–152.

Henry, L. (1961). Some data on natural fertility. Eugenics Quarterly 8(2): 81–91.

Stone, L. (2023). Ultra-Orthodox fertility and marriage in the United States: Evidence from the American Community Survey. Demographic Research 49(29): 769–782.


Figure 1 (see PDF)

25 January 2024 | Response Letter

Fertility of Ultra-Orthodox Jews in USA

by Michel Garenne

Fertility of Ultra-Orthodox Jews in USA

The paper by Lyman Stone presents the case of an ethno-linguistic group with very high fertility in the USA, identified in the American Community Survey (ACS) [Stone 2023]. This case study was rather unexpected in a developed country in the 21st century. This group is labeled ‘Haredi’, who are ultra-Orthodox Jews, defined by speaking Yiddish at home. Other such groups with outstanding fertility were documented in the past, the most well known being the Hutterites, who so far hold the world record of marital fertility, and are used as a reference of maximum natural fertility [Eaton and Meyer 1953]. We calculated the fertility rates (births last year / women) by ethnolinguistic group in the USA from all 22 ACS surveys available, using the IPUMS-USA on-line facility [Ruggles et al. 2013]. The fertility of the Haredi (TFR= 7.13) appears way above any other ethno-linguistic group in the USA over the 2000-2021 period, the next groups being ‘Hamitic’ (East-Africans) (TFR= 4.73), and ‘Shoshonean/Hopi’ (American Natives) (TFR = 4.68). Stone discusses the question whether the Haredi fertility is natural or hides some fertility control.

Here, using the same dataset, we compared the marital fertility (births last year / married women) of the Haredi with that of the Hutterites (1926–1940) and with that of the rural population of Niger (1982–2012), also known as a record high fertility (TFR= 8.56) [Garenne 2017]. Figure 1 displays the age patterns of marital fertility from age 20 to 49. The figure clearly shows three parallel patterns of natural fertility, with no family limitation. The Haredi pattern falls 25% below that of the Hutterites, which implies 33% longer birth intervals, and is 12% above that of rural Niger, with implies 10% shorter birth intervals. Several reasons could explain the differences in average length of birth intervals: breastfeeding, post-partum abstinence, short-term post-partum contraception, fecundability, or coital frequency. Note that since there is virtually no contraception in rural Niger, there is no need to invoke contraception for explaining the Haredi pattern. It would be interesting to know the details of this outstanding behavior.

Natural fertility is the result of a social (often religious) ideology imposed on women for maximizing the fertility of the group. It is surprising to see such a behavior emerging in 21st century USA, when most societies underwent a fertility transition leading to low levels around or below replacement. 

Michel Garenne


Eaton, J.W. and Mayer, A.J. (1953). The social biology of very high fertility among the Hutterites: The demography of a unique population. Human Biology 25(3): 206–264.

Garenne, M. (2017). Record high fertility in sub-Saharan Africa in a comparative perspective. African Population Studies 31(2): 3706–3723.

Ruggles, S., Flood, S., Sobek, M., Backman, D., Chen, A., Cooper, G., Richards, S., Rogers, R., and Schouweiler, M. (2023). IPUMS USA: Version 14.0 [dataset]. Minneapolis, MN: IPUMS. https://doi.org/10.18128/D010.V14.0

Stone, L. (2023). Ultra-Orthodox fertility and marriage in the United States: Evidence from the American Community Survey. Demographic Research 49(29): 769–782. DOI:10.4054/DemRes.2023.49.29

Figure 1: Age patterns of marital fertility: Haredi, Hutterites and Niger-rural (see PDF)

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