Ethnic differences in birth gender ratio responses in the United States after the September 11 Attacks and the President Kennedy assassination

Abstract

Introduction: Male exceed female live births. The ratio is expressed as M/F (male/total live births). Many factors influence this ratio including stress, which depresses it. The 9/11 attacks lowered M/F in the United States a few months after the event. This study was carried out to identify any racial differences in the observed M/F reduction. This paper also analysed racial M/F responses to the assassination of President John Kennedy.

Methods: For the JKF assassination, births were available as White and Non-White births. For 9/11, births were available for four racial groups: American Indian/Alaska Native, Asian/Pacific, Black/African and White.

Results: For the JFK assassination (November 1963), total M/F was lowest in 1964 (1958–1970, p ≤ 0.01). M/F dipped in March 1964 in Non-White births only (p < 0.0001). For 9/11, M/F dips showed a nonsignificant gradient, being greater in Asian/Pacific births, followed by White and Black/African. Baseline M/F was Asian/Pacific > White > Black/African and American Indian/Alaska Native.

Discussion: President Kennedy actively attempted to usher in civil rights, and his assassination may have stressed Non-Whites far more than Whites. For 9/11, the low Black/African M/F dips may be due to chronic stress associated with being overall disadvantaged and of lower socio-economic status. These factors decrease M/F and potentially dampen M/F dips in response to additional stressors. The observed M/F dips often exceed the perinatal mortality statistic. Public Health should be more cognizant of the effect of stress on population M/F as a sentinel health indicator.