The Ratio of Male to Female Births as Affected by Wars

Abstract

The theory has been advanced that the proportion of male to female births rises during or just after period of war or similar catastrophe in which the mortality of the males has been unusually heavy, as though nature strove to keep the proportion of the sexes roughly at constant figure. Duising, in supporting his contention that late fertilization of females and increased time intervals between fertilizations tend to result in relatively large number of males, says: fact, we note that after every war there is relative over-abundance of male births. the Napoleonic Wars this phenomenon was so strongly apparent that people feared relative shortage of females. This has long been well known, has been noted after every war, and has never been doubted.'I F. Prinzing refers to this theory also in the Medizinische Statistik (1906), where he writes: After wars the relative number of males is said to be higher. Diusing calls it well-known fact, and Von Fircks draws this conclusion from the German figures after 1866 and 1871.2 This same contention has been brought forward by later statisticians and scientists. In recent presidential address before the Royal Statistical Society, Sir Bernard Mallet presented figures showing that the proportion of male births to female births in England and Wales, Scotland, and Ireland for the years 1915 and 1916 was above the proportion for the twenty years 1894 to 1913. He stated that for the whole period cove,red by these war births the proportion of male to female births in England and Wales was 1,046, or eight above the average for the previous forty years, and concluded that a rise in the sex proportion so marked and sustained over so long period can hardly be dismissed as an accidental coincidence. 3 The British Medical Journal seems to put some faith in the theory, for it states (Nov. 21, 1914, p. 886) that it is remarkable that in 1857, the year after the return of our army from the Crimea, the excess of male over female births was much higher than the average for the three previous and the three subsequent years, and again immediately after the Boer War in 1901-02 it rose above the average for the preceding period, 1897-1900. So general is the interest in this matter