Terrorism and the male to female ratio at birth : “Anni di Piombo” in Italy

Abstract

Introduction: Males are usually born slightly in excess of females and the ratio is often expressed as M/F (male divided by total births). Many factors have been shown to influence M/F, including periods of terrorism which lower M/F through a process of excessive male foetal loss. The Years of Lead constituted a terrorist political phenomenon that commenced in Italy, known as “Anni di Piombo” (1969–1982). This study was carried out in order to ascertain whether the era caused any fluctuations in annual M/F in Italy. Methods: Annual birth data by gender for Italy was obtained from a World Health Organisation Database. Monthly data was unavailable. Results: Annual M/F showed no significant annual dips. However, M/F rose between 1965-69 and 1970-4, and again between 1985-89 and 1990-94 (p<0.01). Discussion: These findings may be due to one of two reasons: a population that is unaffected or less affected by terrorism, or additional factors that may have obscured and even swung M/F upward, in the opposite direction to that expected. A potential explanation is an increase in ambient radiation following a peak of atmospheric bomb testing prior to the Partial Nuclear Test Ban Treaty in 1963, and after Chernobyl in 1986. The rise in M/F in Italy in the early 1970s may have been caused by the former and the rise in the late 1980s may have been caused by the latter. Radiation may be as strong or an even stronger influence on M/F than stress.