Outcome of the 2016 United States presidential election and the subsequent sex ratio at birth in Canada: an ecological study

Abstract

ObjectivesThe 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.DesignEcological study.SettingAdministrative data for Ontario (Canada’s most populous province).ParticipantsAll births in Ontario from April 2010 to Oct 2017 inclusive (n=1 079 758).Primary and secondary outcome measuresWe 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.ResultsIn 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).ConclusionThe 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.

COVID-19 onset reduced the sex ratio at birth in South Africa

“…Our findings are inline with the hypothesis that COVID-19 stress would result in SRB decline ( Abdoli, 2020 ), driven by the Trivers-Willard hypothesis which posits that adverse environmental conditions can lower the ratio of males to females ( Trivers & Willard, 1973 ). Our findings are also consistent with studies that have reported a transient SRB decline 3–5 months following unexpected events which stressed populations acutely ( Calleja, 2020 ; Grech, 2015a ; Grech, 2015b ; Masukume et al, 2017 ; Retnakaran & Ye, 2020 ). A sex ratio at birth of less than 0.5 has also been observed in the 3–5 months following the July 2011 Norway attacks, the December 2012 Sandy Hook Elementary School shooting, and the October 2017 assassination of investigative journalist Daphne Caruana Galizia ( Calleja, 2020 ; Grech, 2015b ).…”

COVID-19 induced birth sex ratio changes in England and Wales

“…This suggests that the SRB decline in England and Wales in June 2020 was not coincidental but rather was being driven by a common factor that simultaneously affected different continents and hemispheres. The finding is consistent with studies that found a transient reduction in SRB 3–5 months after unanticipated occurrences that stressed populations ( Calleja, 2020 ; Catalano et al, 2006 ; Grech, 2015 ; Retnakaran & Ye, 2020 ). As previously mentioned, the unanticipated onset of the COVID-19 pandemic was identified as a substantial population stressor, and it is known that such significant stressors can induce an SRB decrease, hence it is improbable that the June 2020 SRB dip in England and Wales was a random occurrence.…”

“…The increases or decreases have been noted to occur within two distinct time windows. The first window is 3–5 months after sudden and unanticipated stressful events such as terrorist attacks ( Bruckner, Catalano & Ahern, 2010 ), the death of a well-known public person ( Grech, 2015 ), or unexpected national election results ( Retnakaran & Ye, 2020 ). This first window is linked to a disproportionate pregnancy loss of male fetuses, which is reflected in a lower SRB a few months after the stressful event.…”

COVID-19 induced birth sex ratio changes in England and Wales

“…Three months after the COVID-19 pandemic was declared, a decline in the SRB was noted in South Africa in June 2022 (Masukume et al 2022), which is similar to the transient decline in SRB observed in this study in June 2020. This is consistent with studies that found a transient reduction in SRB 3-5 months after unanticipated occurrences that stressed populations (Calleja 2020;Catalano et al 2006;Grech 2015;Retnakaran & Ye 2020).…”

“…The increases or decreases have been noted to occur within two distinct time windows. The first window is 3-5 months after sudden and unanticipated stressful events such as terrorist attacks (Bruckner et al 2010), the death of a well-known public person (Grech 2015), or unexpected national election results (Retnakaran & Ye 2020). This first window is linked to a disproportionate pregnancy loss of male fetuses, which is reflected in a lower SRB a few months after the stressful event.…”