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Sex ratio at birth across 100 years in Sweden and risk of cardiovascular disease and all-cause mortality – a national register study

Nilsson, Peter M. LU ; Sundquist, Kristina LU ; Sundquist, Jan LU ; Crump, Casey LU and Li, Xinjun LU (2024) In European Journal of Epidemiology 39(9). p.967-976
Abstract

The human sex ratio at birth (SRB) undergoes temporary changes around a mean proportion of 0.51 male births. SRB has been well studied for historical, geographical, and secular trends, but until now not linked to health outcomes in the total population, e.g. for cardiovascular disease (CVD) or mortality during follow-up of birth cohorts. We used linkage analysis based on national registers in Sweden that cover all births from 1900 to 2016. SRB at birth was calculated by every 10-year birth cohort in all survivors living in 1997 for a follow-up analysis of risk of CVD and mortality with data from national registers. When the highest quartile of SRB was used as reference, a slightly increased risk of fatal CVD (HR 1.03 (95% confidence... (More)

The human sex ratio at birth (SRB) undergoes temporary changes around a mean proportion of 0.51 male births. SRB has been well studied for historical, geographical, and secular trends, but until now not linked to health outcomes in the total population, e.g. for cardiovascular disease (CVD) or mortality during follow-up of birth cohorts. We used linkage analysis based on national registers in Sweden that cover all births from 1900 to 2016. SRB at birth was calculated by every 10-year birth cohort in all survivors living in 1997 for a follow-up analysis of risk of CVD and mortality with data from national registers. When the highest quartile of SRB was used as reference, a slightly increased risk of fatal CVD (HR 1.03 (95% confidence intervals, CI): 1.02–1.04), non-fatal CVD (HR 1.01; 95%CI: 1.01–1.02) and mortality (HR 1.02; 95%CI, 1.01–1.03) was found after full adjustments in men belonging to the lowest SRB quartile. A similar pattern was also found for fatal CHD in women. in the lowest SBR quartile compared to the highest, HR 1.03 (95%CI: 1.02–1.05). In conclusion, in birth cohorts with a relatively lower than expected number of males born, long-term adverse health effects were observed with slightly increased cardiovascular risk and total mortality at the population level. This could indicate that men belonging to so-called “culled cohorts” in a developed country during the 20th century are characterized by a slightly increased risk that could reflect negative early life influences and environmental exposures in pregnant women resulting in selective loss of male embryos or fetuses. In a public health perspective SRB could be of some importance to monitor as an aspect of birth statistics linked to relatively minor population health effects.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cardiovascular disease, Epidemiology, Mortality, Registers, Sex ratio at birth, Time trends
in
European Journal of Epidemiology
volume
39
issue
9
pages
10 pages
publisher
Springer
external identifiers
  • scopus:85198512026
  • pmid:39004637
ISSN
0393-2990
DOI
10.1007/s10654-024-01137-1
language
English
LU publication?
yes
additional info
Publisher Copyright: © The Author(s) 2024.
id
0605fc53-7f8b-495e-a881-cb06594cd87c
date added to LUP
2024-12-04 11:55:50
date last changed
2025-12-18 20:53:19
@article{0605fc53-7f8b-495e-a881-cb06594cd87c,
  abstract     = {{<p>The human sex ratio at birth (SRB) undergoes temporary changes around a mean proportion of 0.51 male births. SRB has been well studied for historical, geographical, and secular trends, but until now not linked to health outcomes in the total population, e.g. for cardiovascular disease (CVD) or mortality during follow-up of birth cohorts. We used linkage analysis based on national registers in Sweden that cover all births from 1900 to 2016. SRB at birth was calculated by every 10-year birth cohort in all survivors living in 1997 for a follow-up analysis of risk of CVD and mortality with data from national registers. When the highest quartile of SRB was used as reference, a slightly increased risk of fatal CVD (HR 1.03 (95% confidence intervals, CI): 1.02–1.04), non-fatal CVD (HR 1.01; 95%CI: 1.01–1.02) and mortality (HR 1.02; 95%CI, 1.01–1.03) was found after full adjustments in men belonging to the lowest SRB quartile. A similar pattern was also found for fatal CHD in women. in the lowest SBR quartile compared to the highest, HR 1.03 (95%CI: 1.02–1.05). In conclusion, in birth cohorts with a relatively lower than expected number of males born, long-term adverse health effects were observed with slightly increased cardiovascular risk and total mortality at the population level. This could indicate that men belonging to so-called “culled cohorts” in a developed country during the 20th century are characterized by a slightly increased risk that could reflect negative early life influences and environmental exposures in pregnant women resulting in selective loss of male embryos or fetuses. In a public health perspective SRB could be of some importance to monitor as an aspect of birth statistics linked to relatively minor population health effects.</p>}},
  author       = {{Nilsson, Peter M. and Sundquist, Kristina and Sundquist, Jan and Crump, Casey and Li, Xinjun}},
  issn         = {{0393-2990}},
  keywords     = {{Cardiovascular disease; Epidemiology; Mortality; Registers; Sex ratio at birth; Time trends}},
  language     = {{eng}},
  number       = {{9}},
  pages        = {{967--976}},
  publisher    = {{Springer}},
  series       = {{European Journal of Epidemiology}},
  title        = {{Sex ratio at birth across 100 years in Sweden and risk of cardiovascular disease and all-cause mortality – a national register study}},
  url          = {{http://dx.doi.org/10.1007/s10654-024-01137-1}},
  doi          = {{10.1007/s10654-024-01137-1}},
  volume       = {{39}},
  year         = {{2024}},
}