A review of terrorism and its reduction of the gender ratio at birth after seasonal adjustment

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

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.

The Paradoxical Effects of Hurricane Katrina on Births and Adverse Birth Outcomes

Objectives. To review the trends in pregnancy outcomes after Hurricane Katrina and assess effects of the disaster on research and public health related to pregnant women.Methods. We reexamined the 2004-2006 vital statistics data from Alabama, Louisiana, and Mississippi, assessing what the risk of adverse pregnancy outcomes in the population would have been under varying risk scenarios.Results. We saw a reduction in number of births as well as in low birth weight and preterm birth. If the number of births had stayed constant and the relative higher risk in the "missing" births had been between 17% and 100%, the storm would have been associated with an increased risk instead of a decrease. Because the relative decline in births was larger in Black women, the higher risk in the "missing" births required to create a significant increase associated with the storm was generally not as great as for White women.Conclusions. Higher exposure to Katrina may have produced a reduction in births among high-risk women in the region rather than increasing adverse outcomes among those who did give birth.

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

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.