{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T19:16:53Z","timestamp":1792783013921,"version":"4.5.0"},"reference-count":56,"publisher":"Springer Science and Business Media LLC","issue":"8","license":[{"start":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T00:00:00Z","timestamp":1779840000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T00:00:00Z","timestamp":1779840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"name":"University of Turku","id":[{"id":"https:\/\/ror.org\/05vghhr25","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Eur J Epidemiol"],"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Exogenous shocks experienced by the population like armed conflicts, natural disasters and economic downturns have all been suggested to correlate with variation in human sex ratio at birth, either through sex-specific embryonic mortality and\/or primary sex adjustment. Recently experienced COVID-19 pandemic has also been related to changes in birth sex ratio in some countries but the results have been mixed. In the aftermath of the pandemic, Russia\u2019s attack on Ukraine caused further emotional anxiety and economic hardship in Europe. This was also true in Finland, which has had a decade-long close trading history with its neighboring state, Russia. Here, we examined the influence of this \u201cdouble trouble\u201d on variation in proportion of males born alive as well as male proportion of stillbirths in Finland during 2000\u20132024, using high-quality monthly census panel data covering the entire Finnish population (a total of 1,355,037 live births and 4,096 stillbirths). The results from Bayesian aggregated binomial time-series regressions showed no evidence for COVID-19-related associations on either the proportion of male live births or stillbirths. We did find an increased proportion of males born alive after 4 months of Russia\u2019s offensive but this finding should be considered as exploratory rather than confirmatory. If proportion of male live births or stillbirths can be regarded as a health indicator of the population, our results suggest that Finland as a society showed marked resilience in terms of non-responsive sex ratios when facing these two adverse exogenous shocks.<\/jats:p>","DOI":"10.1007\/s10654-026-01407-0","type":"journal-article","created":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T07:13:58Z","timestamp":1779866038000},"page":"1019-1028","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["The decade of double-trouble: live birth and stillbirth sex ratio variation in Finland during the COVID-19 pandemic and Russia\u2019s attack on Ukraine"],"prefix":"10.1007","volume":"41","author":[{"given":"Samuli","family":"Helle","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antti O.","family":"Tanskanen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mirkka","family":"Danielsbacka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,5,27]]},"reference":[{"key":"1407_CR1","doi-asserted-by":"publisher","first-page":"48","DOI":"10.1017\/CBO9780511542053.004","volume-title":"Sex Ratios: Concepts and Research Methods","author":"K Wilson","year":"2002","unstructured":"Wilson K, Hardy ICW. Statistical analysis of sex ratios: an introduction. In: Hardy ICW, editor. Sex Ratios: Concepts and Research Methods. Cambridge: Cambridge University Press; 2002. pp. 48\u201392."},{"key":"1407_CR2","doi-asserted-by":"publisher","first-page":"50","DOI":"10.1016\/j.earlhumdev.2017.03.002","volume":"109","author":"WH James","year":"2017","unstructured":"James WH, Grech V. A review of the established and suspected causes of variations in human sex ratio at birth. Early Hum Dev. 2017;109:50\u20136.","journal-title":"Early Hum Dev"},{"key":"1407_CR3","doi-asserted-by":"publisher","first-page":"104859","DOI":"10.1016\/j.earlhumdev.2019.104859","volume":"140","author":"M Fukuda","year":"2020","unstructured":"Fukuda M, Fukuda K, Mason S, Shimizu T, Andersen CY. Effects of earthquakes and other natural catastrophic events on the sex ratio of newborn infants. Early Hum Dev. 2020;140:104859.","journal-title":"Early Hum Dev"},{"key":"1407_CR4","doi-asserted-by":"publisher","first-page":"e23846","DOI":"10.1002\/ajhb.23846","volume":"35","author":"C Parayiwa","year":"2022","unstructured":"Parayiwa C, Harley D, Richardson A, Behie A. Severe cyclones and sex-specific birth outcomes in Queensland, Australia: An interrupted time\u2010series analysis. Am J Hum Biol. 2022;35:e23846. https:\/\/doi.org\/10.1002\/ajhb.23846.","journal-title":"Am J Hum Biol"},{"key":"1407_CR5","doi-asserted-by":"publisher","first-page":"e24003","DOI":"10.1002\/ajhb.24003","volume":"36","author":"L Fontanesi","year":"2024","unstructured":"Fontanesi L, Verrocchio MC, D\u2019Ettore M, Prete G, Ceravolo F, Marchetti D. The impact of catastrophic events on the sex ratio at birth: A systematic review. Am J Hum Biol. 2024;36:e24003. https:\/\/doi.org\/10.1002\/ajhb.24003.","journal-title":"Am J Hum Biol"},{"key":"1407_CR6","doi-asserted-by":"publisher","first-page":"60","DOI":"10.1098\/rsbl.2007.0482","volume":"4","author":"S Helle","year":"2008","unstructured":"Helle S, Helama S, Jokela J. Temperature-related birth sex ratio bias in historical Sami: warm years bring more sons. Biol Lett. 2008;4:60\u20132.","journal-title":"Biol Lett"},{"key":"1407_CR7","doi-asserted-by":"publisher","first-page":"1226","DOI":"10.1111\/j.1365-2656.2009.01598.x","volume":"78","author":"S Helle","year":"2009","unstructured":"Helle S, Helama S, Lertola K. Evolutionary ecology of human birth sex ratio under the compound influence of climate change, famine, economic crises and wars. J Anim Ecol. 2009;78:1226\u201333.","journal-title":"J Anim Ecol"},{"key":"1407_CR8","first-page":"2883","volume":"279","author":"S Song","year":"2012","unstructured":"Song S. Does famine influence sex ratio at birth? Evidence from the 1959\u20131961 Great Leap Forward Famine in China. Proc Biol Sci. 2012;279:2883\u201390.","journal-title":"Proc Biol Sci"},{"key":"1407_CR9","doi-asserted-by":"publisher","first-page":"944","DOI":"10.1093\/ije\/dyi081","volume":"34","author":"RA Catalano","year":"2005","unstructured":"Catalano RA, Bruckner T, Anderson E, Gould JB. Fetal death sex ratios: a test of the economic stress hypothesis. Int J Epidemiol. 2005;34:944\u20138.","journal-title":"Int J Epidemiol"},{"key":"1407_CR10","doi-asserted-by":"publisher","first-page":"101","DOI":"10.1016\/j.ssmph.2018.05.010","volume":"5","author":"TA Bruckner","year":"2018","unstructured":"Bruckner TA, Catalano RA. Selection in utero and population health: theory and typology of research. SSM Popul Health. 2018;5:101\u201313.","journal-title":"SSM Popul Health"},{"key":"1407_CR11","doi-asserted-by":"publisher","first-page":"65","DOI":"10.1006\/jtbi.1999.1044","volume":"202","author":"JC Wells","year":"2000","unstructured":"Wells JC. Natural selection and sex differences in morbidity and mortality in early life. J Theor Biol. 2000;202:65\u201376.","journal-title":"J Theor Biol"},{"key":"1407_CR12","doi-asserted-by":"publisher","first-page":"475","DOI":"10.1016\/j.jtbi.2008.12.008","volume":"257","author":"RA Catalano","year":"2009","unstructured":"Catalano RA, Saxton K, Bruckner T, Goldman S, Anderson E. A sex-specific test of selection in utero. J Theor Biol. 2009;257:475\u20139.","journal-title":"J Theor Biol"},{"key":"1407_CR13","doi-asserted-by":"publisher","first-page":"23877","DOI":"10.1073\/pnas.1916909116","volume":"116","author":"MM McCarthy","year":"2019","unstructured":"McCarthy MM. Stress during pregnancy: Fetal males pay the price. Proc Natl Acad Sci U S A. 2019;116:23877\u20139. https:\/\/doi.org\/10.1073\/pnas.1916909116.","journal-title":"Proc Natl Acad Sci U S A"},{"key":"1407_CR14","doi-asserted-by":"publisher","first-page":"902","DOI":"10.1017\/s2040174420001300","volume":"12","author":"B Romero-Gonzalez","year":"2021","unstructured":"Romero-Gonzalez B, Puertas\u2010Gonzalez JA, Gonzalez\u2010Perez R, Davila M, Peralta\u2010Ramirez MI. Hair cortisol levels in pregnancy as a possible determinant of fetal sex: A longitudinal study. J Dev Orig Health Dis. 2021;12:902\u20137. https:\/\/doi.org\/10.1017\/s2040174420001300.","journal-title":"J Dev Orig Health Dis"},{"key":"1407_CR15","doi-asserted-by":"crossref","unstructured":"Melaku M, Juvinao-Quintero DL, Sanchez SE, Rondon MB, Kirschbaum C, Williams MA et al. Association of preconception maternal glucocorticoid concentrations with sex ratio at birth: Evidence from a prospective cohort study. Ann Epidemiol. 2025; In press.","DOI":"10.1016\/j.annepidem.2025.05.011"},{"key":"1407_CR16","doi-asserted-by":"publisher","first-page":"1018","DOI":"10.1001\/jama.279.13.1018","volume":"279","author":"DL Davis","year":"1998","unstructured":"Davis DL, Gottlieb MB, Stampnitzky JR. Reduced ratio of male to female births in several industrial countries: a sentinel health indicator? JAMA. 1998;279:1018\u201323.","journal-title":"JAMA"},{"key":"1407_CR17","doi-asserted-by":"publisher","first-page":"22","DOI":"10.1016\/j.earlhumdev.2018.02.002","volume":"118","author":"V Grech","year":"2018","unstructured":"Grech V. Correlation of sex ratio at birth with health and socioeconomic indicators. Early Hum Dev. 2018;118:22\u20134. https:\/\/doi.org\/10.1016\/j.earlhumdev.2018.02.002.","journal-title":"Early Hum Dev"},{"key":"1407_CR18","doi-asserted-by":"publisher","first-page":"23","DOI":"10.1111\/padr.12544","volume":"50","author":"T Sobotka","year":"2024","unstructured":"Sobotka T, Zeman K, Jasilioniene A, Winkler-Dworak M, Brzozowska Z, Alustizia-Galarza A, et al. Pandemic Roller-Coaster? Birth Trends in Higher-Income Countries During the COVID-19 Pandemic. Popul Dev Rev. 2024;50:23\u201358. https:\/\/doi.org\/10.1111\/padr.12544.","journal-title":"Popul Dev Rev"},{"key":"1407_CR19","doi-asserted-by":"publisher","first-page":"e14618","DOI":"10.7717\/peerj.14618","volume":"11","author":"G Masukume","year":"2023","unstructured":"Masukume G, Ryan M, Masukume R, Zammit D, Grech V, Mapanga W, et al. COVID-19 induced birth sex ratio changes in England and Wales. PeerJ. 2023;11:e14618.","journal-title":"PeerJ"},{"key":"1407_CR20","doi-asserted-by":"publisher","first-page":"e13985","DOI":"10.7717\/peerj.13985","volume":"10","author":"G Masukume","year":"2022","unstructured":"Masukume G, Ryan M, Masukume R, Zammit D, Grech V, Mapanga W. COVID-19 onset reduced the sex ratio at birth in South Africa. PeerJ. 2022;10:e13985.","journal-title":"PeerJ"},{"key":"1407_CR21","doi-asserted-by":"publisher","first-page":"e23750","DOI":"10.1002\/ajhb.23750","volume":"34","author":"Y Inoue","year":"2022","unstructured":"Inoue Y, Mizoue T. A preliminary analysis of the secondary sex ratio decline after the COVID-19 pandemic in Japan. Am J Hum Biol. 2022;34:e23750.","journal-title":"Am J Hum Biol"},{"key":"1407_CR22","doi-asserted-by":"publisher","first-page":"e24159","DOI":"10.1002\/ajhb.24159","volume":"36","author":"G Masukume","year":"2024","unstructured":"Masukume G, Non AL, Cleaver P, Grech V. The impact of the covid-19 pandemic in the sex ratio at birth in Ireland. Am J Hum Biol. 2024;36:e24159. https:\/\/doi.org\/10.1002\/ajhb.24159.","journal-title":"Am J Hum Biol"},{"key":"1407_CR23","doi-asserted-by":"publisher","first-page":"572","DOI":"10.3390\/ijerph21050572","volume":"21","author":"D Pavi\u0107","year":"2024","unstructured":"Pavi\u0107 D. Sex ratio at birth after concurrent events of earthquakes and the COVID-19 pandemic in Croatia. Int J Environ Res Public Health. 2024;21:572. https:\/\/doi.org\/10.3390\/ijerph21050572.","journal-title":"Int J Environ Res Public Health"},{"key":"1407_CR24","doi-asserted-by":"publisher","first-page":"e22043","DOI":"10.1002\/evan.22043","volume":"33","author":"P Cleaver","year":"2024","unstructured":"Cleaver P, Non AL. Were fewer boys born in the United States during the early months of the COVID-19 pandemic? A test of the Trivers-Willard hypothesis. Evol Anthropol. 2024;33:e22043. https:\/\/doi.org\/10.1002\/evan.22043.","journal-title":"Evol Anthropol"},{"key":"1407_CR25","doi-asserted-by":"publisher","first-page":"374","DOI":"10.1093\/emph\/eoab033","volume":"9","author":"RA Catalano","year":"2021","unstructured":"Catalano RA, Bruckner T, Casey JA, Gemmill A, Margerison C, Hartig T. Twinning during the pandemic: evidence of selection in utero. Evol Med Public Health. 2021;9:374\u201382.","journal-title":"Evol Med Public Health"},{"key":"1407_CR26","doi-asserted-by":"publisher","first-page":"e23830","DOI":"10.1002\/ajhb.23830","volume":"35","author":"TA Bruckner","year":"2023","unstructured":"Bruckner TA, Bustos B, Margerison C, Gemmill A, Casey J, Catalano RA. Selection in utero against male twins in the United States early in the COVID-19 pandemic. Am J Hum Biol. 2023;35:e23830.","journal-title":"Am J Hum Biol"},{"key":"1407_CR27","doi-asserted-by":"publisher","first-page":"702","DOI":"10.1111\/padr.12715","volume":"51","author":"ML Caudillo","year":"2025","unstructured":"Caudillo ML, Villareal A, Torche F. Individual Behaviors and Health Inequalities: Preterm Birth During the COVID-19 Pandemic in Mexico. Popul Dev Rev. 2025;51:702\u201334.","journal-title":"Popul Dev Rev"},{"key":"1407_CR28","doi-asserted-by":"publisher","first-page":"90","DOI":"10.1126\/science.179.4068.90","volume":"179","author":"RL Trivers","year":"1973","unstructured":"Trivers RL, Willard DE. Natural selection of parental ability to vary the sex ratio of offspring. Science. 1973;179:90\u20132.","journal-title":"Science"},{"key":"1407_CR29","doi-asserted-by":"publisher","first-page":"E2102","DOI":"10.1073\/pnas.1416546112","volume":"112","author":"SH Orzack","year":"2015","unstructured":"Orzack SH, Stubblefield JW, Akmaev VR, Zuckerman JE. The human sex ratio from conception to birth. Proc Natl Acad Sci U S A. 2015;112:E2102\u201311.","journal-title":"Proc Natl Acad Sci U S A"},{"key":"1407_CR30","doi-asserted-by":"publisher","first-page":"1133","DOI":"10.1093\/humrep\/deg220","volume":"18","author":"WH James","year":"2003","unstructured":"James WH. Sex Ratios of Births Conceived During Wartime. Hum Reprod. 2003;18:1133\u20134. https:\/\/doi.org\/10.1093\/humrep\/deg220.","journal-title":"Hum Reprod"},{"key":"1407_CR31","doi-asserted-by":"publisher","first-page":"3157","DOI":"10.1186\/s12889-024-20416-w","volume":"24","author":"SM Zhou","year":"2024","unstructured":"Zhou SM, Ahmadi H, Huo L, Lix LM, Maslin K, Latour JM, et al. COVID-19 and pregnancy: a comprehensive study of comorbidities and outcomes. BMC Public Health. 2024;24:3157. https:\/\/doi.org\/10.1186\/s12889-024-20416-w.","journal-title":"BMC Public Health"},{"key":"1407_CR32","doi-asserted-by":"publisher","first-page":"68","DOI":"10.1016\/j.ajog.2021.07.009","volume":"226","author":"A Conde-Agudelo","year":"2022","unstructured":"Conde-Agudelo A, Romero R. SARS-CoV-2 infection during pregnancy and risk of preeclampsia: a systematic review and meta-analysis. Am J Obstet Gynecol. 2022;226:68\u2013e893. https:\/\/doi.org\/10.1016\/j.ajog.2021.07.009.","journal-title":"Am J Obstet Gynecol"},{"key":"1407_CR33","doi-asserted-by":"publisher","first-page":"1983","DOI":"10.1001\/jama.2022.5906","volume":"327","author":"E McClymont","year":"2022","unstructured":"McClymont E, Albert AY, Alton GD, Boucoiran I, Castillo E, Fell DB, et al. Association of SARS-CoV-2 Infection during Pregnancy With Maternal and Perinatal Outcomes. JAMA. 2022;327:1983\u201391.","journal-title":"JAMA"},{"key":"1407_CR34","doi-asserted-by":"publisher","first-page":"3234","DOI":"10.1038\/s41467-024-47181-z","volume":"15","author":"HM Engjom","year":"2024","unstructured":"Engjom HM, Ramakrishnan R, Vousden N, Bunch K, Morris E, Simpson N, et al. Perinatal outcomes after admission with COVID-19 in pregnancy: a UK national cohort study. Nat Commun. 2024;15:3234.","journal-title":"Nat Commun"},{"key":"1407_CR35","doi-asserted-by":"publisher","first-page":"e59","DOI":"10.1017\/S0950268825000354","volume":"153","author":"A Suomenrinne-Nordvik","year":"2025","unstructured":"Suomenrinne-Nordvik A, Leino T, Shubin M, Auranen K, V\u00e4nsk\u00e4 S. Quantifying the direct and indirect components of COVID-19 vaccine effectiveness during the Delta variant era. Epidemiol Infect. 2025;153:e59. https:\/\/doi.org\/10.1017\/S0950268825000354.","journal-title":"Epidemiol Infect"},{"key":"1407_CR36","doi-asserted-by":"publisher","first-page":"1933","DOI":"10.1038\/s41591-022-01887-z","volume":"28","author":"JA Lewnard","year":"2022","unstructured":"Lewnard JA, Hong VX, Patel MM, Kahn R, Lipsitch M, Tartof SY. Clinical outcomes associated with SARS-CoV-2 omicron (B.1.1.529) variant and BA.1\/BA.1.1 or BA.2 subvariant infection in Southern California. Nat Med. 2022;28:1933\u201343. https:\/\/doi.org\/10.1038\/s41591-022-01887-z.","journal-title":"Nat Med"},{"key":"1407_CR37","unstructured":"Anttonen J, Lehmus M. Geopoliittisten shokkien v\u00e4littyminen Suomen inflaatioon ja bruttokansantuotteeseen [Transmission of geopolitical shocks to Finnish inflation and gross domestic product]. BoF Econ Rev. 2025;2. Available from: https:\/\/urn.fi\/URN:NBN:fi-fe2025090193449"},{"key":"1407_CR38","doi-asserted-by":"publisher","first-page":"1","DOI":"10.18637\/jss.v080.i01","volume":"80","author":"PC B\u00fcrkner","year":"2017","unstructured":"B\u00fcrkner PC. brms: An R Package for Bayesian Multilevel Models using Stan. J Stat Softw. 2017;80:1\u201328. https:\/\/doi.org\/10.18637\/jss.v080.i01.","journal-title":"J Stat Softw"},{"key":"1407_CR39","doi-asserted-by":"publisher","DOI":"10.1201\/9780429029608","volume-title":"Statistical rethinking: A Bayesian course with examples in R and Stan","author":"R McElreath","year":"2020","unstructured":"McElreath R. Statistical rethinking: A Bayesian course with examples in R and Stan. 2nd ed. Boca Raton: CRC; 2020.","edition":"2"},{"key":"1407_CR40","doi-asserted-by":"publisher","DOI":"10.1201\/9781315370279","volume-title":"Generalized Additive Models: An Introduction with R","author":"S Wood","year":"2017","unstructured":"Wood S. Generalized Additive Models: An Introduction with R. 2nd ed. New York: Chapman and Hall\/CRC; 2017.","edition":"2"},{"key":"1407_CR41","doi-asserted-by":"publisher","first-page":"457","DOI":"10.1214\/ss\/1177011136","volume":"7","author":"A Gelman","year":"1992","unstructured":"Gelman A, Rubin D. Inference from iterative simulation using multiple sequences. Statist Sci. 1992;7:457\u201372. https:\/\/doi.org\/10.1214\/ss\/1177011136.","journal-title":"Statist Sci"},{"key":"1407_CR42","doi-asserted-by":"publisher","first-page":"404","DOI":"10.1016\/j.jtbi.2014.08.004","volume":"363","author":"WH James","year":"2014","unstructured":"James WH, Valentine J. A further note on the rises in sex ratio at birth during and just after the two World Wars. J Theor Biol. 2014;363:404\u201311. https:\/\/doi.org\/10.1016\/j.jtbi.2014.08.004.","journal-title":"J Theor Biol"},{"key":"1407_CR43","doi-asserted-by":"publisher","first-page":"25","DOI":"10.51815\/fjsr.120361","volume":"15","author":"J Nis\u00e9n","year":"2022","unstructured":"Nis\u00e9n J, Jalovaara M, Rotkirch A, Gissler M. Fertility Recovery despite the COVID-19 Pandemic in Finland? Finn J Soc Res. 2022;15:25\u201344. https:\/\/doi.org\/10.51815\/fjsr.120361.","journal-title":"Finn J Soc Res"},{"key":"1407_CR44","doi-asserted-by":"publisher","first-page":"129","DOI":"10.1111\/padr.12539","volume":"50","author":"T Lappeg\u00e5rd","year":"2024","unstructured":"Lappeg\u00e5rd T, Kornstad T, Dommermuth L, Kristensen AP. Understanding the positive effects of the COVID-19 pandemic on women\u2019s fertility in Norway. Popul Dev Rev. 2024;50:129\u201352. https:\/\/doi.org\/10.1111\/padr.12539.","journal-title":"Popul Dev Rev"},{"key":"1407_CR45","doi-asserted-by":"publisher","first-page":"e70029","DOI":"10.1111\/ele.70029","volume":"28","author":"JB Grace","year":"2025","unstructured":"Grace JB, Huntington-Klein N, Schweiger EW, Martinez M, Osland MJ, Feher LC, et al. Causal effects versus causal mechanisms: two traditions with different requirements and contributions towards causal understanding. Ecol Lett. 2025;28:e70029. https:\/\/doi.org\/10.1111\/ele.70029.","journal-title":"Ecol Lett"},{"key":"1407_CR46","doi-asserted-by":"publisher","first-page":"391","DOI":"10.1257\/jel.20191450","volume":"59","author":"A Abadie","year":"2021","unstructured":"Abadie A. Using Synthetic Controls: Feasibility, Data Requirements, and Methodological Aspects. J Econ Lit. 2021;59:391\u2013425. https:\/\/doi.org\/10.1257\/jel.20191450.","journal-title":"J Econ Lit"},{"key":"1407_CR47","doi-asserted-by":"publisher","first-page":"eabg5298","DOI":"10.1126\/science.abg5298","volume":"372","author":"GE Mena","year":"2021","unstructured":"Mena GE, Martinez PP, Mahmud AS, Marquet PA, Buckee CO, Santillana M. Socioeconomic status determines COVID-19 incidence and related mortality in Santiago, Chile. Science. 2021;372:eabg5298. https:\/\/doi.org\/10.1126\/science.abg5298.","journal-title":"Science"},{"key":"1407_CR48","doi-asserted-by":"publisher","first-page":"2334","DOI":"10.1093\/cid\/ciaa815","volume":"9","author":"DB Geno Tai","year":"2021","unstructured":"Geno Tai DB, Sia IG, Doubeni CA, Wieland ML. Disproportionate Impact of COVID-19 on Racial and Ethnic Minority Groups in the United States: a 2021 Update. J Racial Ethn Health Disparities. 2021;9:2334\u20139. https:\/\/doi.org\/10.1093\/cid\/ciaa815.","journal-title":"J Racial Ethn Health Disparities"},{"key":"1407_CR49","doi-asserted-by":"publisher","first-page":"1086","DOI":"10.1016\/j.leaqua.2010.10.010","volume":"21","author":"J Antonakis","year":"2010","unstructured":"Antonakis J, Bendahan S, Jacquart P, Lalive R. On making causal claims: A review and recommendations. Leadersh Q. 2010;21:1086\u2013120. https:\/\/doi.org\/10.1016\/j.leaqua.2010.10.010.","journal-title":"Leadersh Q"},{"key":"1407_CR50","doi-asserted-by":"publisher","first-page":"287","DOI":"10.1017\/CBO9780511542053.015","volume-title":"Sex Ratios: Concepts and Research Methods","author":"J Lazarus","year":"2002","unstructured":"Lazarus J. Human sex ratios: Adaptations and mechanisms, problems and prospects. In: Hardy ICW, editor. Sex Ratios: Concepts and Research Methods. Cambridge: Cambridge University Press; 2002. pp. 287\u2013311."},{"key":"1407_CR51","doi-asserted-by":"publisher","first-page":"23","DOI":"10.1016\/S1472-6483(10)60546-9","volume":"15","author":"L Cronk","year":"2007","unstructured":"Cronk L. Boy or girl: Gender preferences from a Darwinian point of view. Reprod Biomed Online. 2007;15:23\u201332. https:\/\/doi.org\/10.1016\/S1472-6483(10)60546-9.","journal-title":"Reprod Biomed Online"},{"key":"1407_CR52","first-page":"188","volume-title":"The Oxford Handbook of Evolutionary Family Psychology","author":"C Salmon","year":"2021","unstructured":"Salmon C, Hehman J. The Trivers\u2013Willard hypothesis. In: Salmon C, Shackelford TK, editors. The Oxford Handbook of Evolutionary Family Psychology. Oxford: Oxford University Press; 2021. pp. 188\u2013204."},{"key":"1407_CR53","doi-asserted-by":"publisher","first-page":"20192849","DOI":"10.1098\/rspb.2019.2849","volume":"287","author":"BP Zietsch","year":"2020","unstructured":"Zietsch BP, Walum H, Lichtenstein P, Verweij KJH, Kuja-Halkola R. No genetic contribution to variation in human offspring sex ratio: a total population study of 4.7 million births. Proc Roy Soc B. 2020;287:20192849. https:\/\/doi.org\/10.1098\/rspb.2019.2849.","journal-title":"Proc Roy Soc B"},{"key":"1407_CR54","doi-asserted-by":"publisher","first-page":"324","DOI":"10.1016\/j.evolhumbehav.2023.03.005","volume":"44","author":"V Thouzeau","year":"2023","unstructured":"Thouzeau V, Boll\u00e9e J, Cristia A, Chevallier C. Decades of Trivers-Willard research on humans: What conclusions can be drawn? Evol Hum Behav. 2023;44:324\u201331. https:\/\/doi.org\/10.1016\/j.evolhumbehav.2023.03.005.","journal-title":"Evol Hum Behav"},{"key":"1407_CR55","doi-asserted-by":"publisher","DOI":"10.1515\/9781400832019","volume-title":"Sex Allocation","author":"S West","year":"2009","unstructured":"West S. Sex Allocation. Princeton: Princeton University Press; 2009."},{"key":"1407_CR56","doi-asserted-by":"publisher","first-page":"251","DOI":"10.1556\/JEP.7.2009.4.5","volume":"7","author":"VJ Grant","year":"2009","unstructured":"Grant VJ. Wartime sex ratios: Stress, male vulnerability and the interpretation of atypical sex ratio data. J Evol Psychol. 2009;7:251\u201362. https:\/\/doi.org\/10.1556\/JEP.7.2009.4.5.","journal-title":"J Evol Psychol"}],"container-title":["European Journal of Epidemiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s10654-026-01407-0.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1007\/s10654-026-01407-0","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s10654-026-01407-0.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T16:52:37Z","timestamp":1790268757000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1007\/s10654-026-01407-0"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,27]]},"references-count":56,"journal-issue":{"issue":"8","published-print":{"date-parts":[[2026,8]]}},"alternative-id":["1407"],"URL":"https:\/\/doi.org\/10.1007\/s10654-026-01407-0","relation":{},"ISSN":["0393-2990","1573-7284"],"issn-type":[{"value":"0393-2990","type":"print"},{"value":"1573-7284","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,27]]},"assertion":[{"value":"11 August 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"20 April 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"27 May 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"The authors have no relevant financial or non-financial interests to disclose.","order":1,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"This study did not require ethics approval as this is an observational study using population data.","order":2,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Not applicable.","order":3,"name":"Ethics","label":"Consent for publication","group":{"name":"EthicsHeading","label":"Declarations"}}]}}