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Abstract
Objectives The sex ratio at birth (proportion of boys to girls) generally shows slight male preponderance but may decrease in response to societal stressors. Discrete adverse events such as terrorist attacks and disasters typically lead to a temporary decline in the sex ratio 3–5 months later, followed by resolution over around 5 months thereafter. We hypothesised that the unexpected outcome of the 2016 US presidential election may have been a societal stressor for liberal-leaning populations and thereby precipitated such an effect on the sex ratio in Canada.
Design Ecological study.
Setting Administrative data for Ontario (Canada’s most populous province).
Participants All births in Ontario from April 2010 to Oct 2017 inclusive (n=1 079 758).
Primary and secondary outcome measures We determined the sex ratio at birth in Ontario for each month from April 2010 to October 2017 and performed segmented regression analysis to evaluate the seasonally adjusted sex ratio for the following three time periods: before the November 2016 election; after the election to before the anticipated impact; and from anticipated impact to 5 months thereafter.
Results In the 12 months following the election, the lowest sex ratio occurred in March 2017 (4 months post election). Compared with the preceding months, the sex ratio was lower in the 5 months from March to July 2017 (p=0.02) during which time it was rising (p=0.01), reflecting recovery from the nadir. Both effects were seen in liberal-leaning regions of Ontario (lower sex ratio (p=0.006) and recovery (p=0.002) in March–July 2017) but not in conservative-leaning areas (p=0.12 and p=0.49, respectively).
Conclusion The 2016 US presidential election preceded a temporary reduction in the sex ratio at birth in Canada, with the time course of changes therein matching the characteristic pattern of a discrete societal stressor.
- obstetrics
- public health
- epidemiology
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Contributors RR conceived the hypothesis. RR and CY designed the analysis plan. CY performed the analyses. RR wrote the manuscript. Both authors interpreted the data, critically revised the manuscript for important intellectual content, and approved the final manuscript. Both authors had full access to all of the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding This study was supported by intramural funds from the Leadership Sinai Centre for Diabetes.
Disclaimer The funding source had no role in study design, data collection, data analysis, data interpretation, or writing of the report.
Competing interests Both authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: RR reports grants and personal fees from Novo Nordisk, grants from Boehringer Ingelheim, personal fees from Eli Lilly, personal fees from Takeda, personal fees from Sanofi, outside the submitted work.
Patient consent for publication Not required.
Ethics approval This study was approved by the Mount Sinai Hospital Research Ethics Board.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data may be obtained from a third party and are not publicly available. Data are available on request and permission from the Better Outcomes Registry & Network (BORN) (www.bornontario.ca).