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Comparative Study
. 2025 Jul;37(7):e70099.
doi: 10.1002/ajhb.70099.

Sex Ratio at Birth in Northern Ireland During the COVID-19 Pandemic: A Comparison With Published Data From the Republic of Ireland, England and Wales

Gwinyai Masukume  1 , Peyton Cleaver  2 , Roy K Philip  3   4 , Victor Grech  5 , Amy L Non  2
Affiliations
Comparative Study

Sex Ratio at Birth in Northern Ireland During the COVID-19 Pandemic: A Comparison With Published Data From the Republic of Ireland, England and Wales

Gwinyai Masukume et al. Am J Hum Biol. 2025 Jul.

Abstract

Objectives: The COVID-19 pandemic has been linked in several countries to fluctuations in the proportion of male live births/total live births, known as the sex ratio at birth (SRB). This study investigates how the pandemic influenced SRB patterns in Northern Ireland compared to published data from neighboring regions, including the Republic of Ireland with which it shares an open land border, and England and Wales, across the sea.

Methods: Monthly live birth data for Northern Ireland from 2015 to 2021 were obtained from the Northern Ireland Statistics and Research Agency. A time series analysis predicted the SRB for 2020 using data from 2015 to 2019. Predicted and observed SRB values were compared for 2020.

Results: In August 2020, 5 months after the pandemic declaration, the SRB fell significantly to 49.13%, the period's lowest, below the 95% prediction interval (50.09%-51.85%). In December 2020, 9 months after the declaration, the SRB rose to 54.48%, exceeding the prediction interval (49.75%-51.57%). This overall SRB pattern resembled that in England and Wales but differed from the Republic of Ireland.

Conclusion: The decline in SRB in August 2020, occurring 3-5 months after the pandemic declaration, suggests the pandemic disproportionately affected male fetuses in Northern Ireland. The rise in December, 9 months after the declaration, may relate to increased sexual activity in March 2020 following lockdown in a subset of the population. Northern Ireland's SRB pattern aligns more with England and Wales than the Republic of Ireland, indicating that socio-political ties in the United Kingdom may be more influential for pandemic response than geographical proximity.

Keywords: COVID‐19 pandemic; Northern Ireland; male births; sex ratio; stress.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Monthly proportions of male live births from January 2015 to December 2021. The solid orange line highlights data for 2020, while the lines for other years are differentiated as shown in the key.
FIGURE 2
FIGURE 2
Daily average total live births from January 2015 to December 2021. The solid orange line represents data for 2020, while the lines for other years are shown as indicated in the key.
FIGURE 3
FIGURE 3
Observed and predicted sex ratio at birth (SRB) for 2020, with the 95% prediction interval (PI) indicated.
See this image and copyright information in PMC

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