Two World Wars and Belgium: Missing Births and Birth Sex Ratio Changes

Introduction: The sex ratio at birth (male/total births, M/T) is expected to approximate 0.515. M/T is influenced by many factors including stress. Both World Wars have been implicated as influencing birth rates and M/T. This study was carried out to analyse the effects of two World Wars on Belgium vis-à-vis missing births as well as M/T changes. Methods: Belgian male and female births were available for 1830–2019 and annual population was available from Statista. ARIMA models were used to estimate and project birth losses. The effect of wars was assumed to begin in the years following the commencement of each war and extend to the year after cessation of hostilities i.e., 1915–1919 and 1940–1946 for the First and Second World Wars respectively. Results: This study included 27,346,178 live births for 1830–2019, M/T 0.5124. There was a decreasing trend in births for 1830–2019, significant for 1950–2019. There were dips in births in association with both Wars resulting in over 440,000 missing births, 3.80% of the Belgian population for the First World War and 1.91% for the Second World War. M/T rose non-significantly for the First World War and significantly for the Second World War. Discussion: The declining birth rate and M/T in developed countries is a recognised phenomenon. The missing births in relation to wars are of demographic importance but are often overlooked with emphasis usually on casualties and deaths. M/T may rise in wars, possibly due to increased coital activity as well as other factors.