1 Department of Medical Statistics, Epidemiology and Medical Informatics, Andrija Stampar School of Public Health, Medical School, University of Zagreb, Rockefellerova 4, 10 000 Zagreb, Croatia, 2 Department of Public Health Sciences, University of Edinburgh Medical School, Teviot Place, Edinburgh EH8 9AG, UK and 3 Croatian Institute of Public Health, Rockefellerova 7, 10 000 Zagreb, Croatia
4 To whom correspondence should be addressed. Email: opolasek{at}snz.hr
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: birth/male proportion/sex ratio/war
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The war in Croatia began in 1991, and was marked by fierce warfare in distinct parts of the country during 19911993. Among 21 administrative counties of Croatia, 10 were involved in the warfare, while the remaining counties were either involved in moderate warfare or were entirely spared. During most of 1993 and 1994, a status quo remained with about a third of Croatia's territory occupied, until the two short military actions in 1995 led to a full reintegration of the occupied territories (Labar et al., 2004). In this paper, we investigated sex ratio at birth during pre-war, wartime and post-war Croatia.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
As the current administrative territorial subdivision into counties has only been in place since 1993, the data for smaller territorial units (Opcina) for the period 19861992 was compiled and merged to correspond to the current scheme, not affecting the methods of collection or interpretation of statistical data.
Study periods were defined as: pre-war (19861990), wartime (19911997), and post-war (19982002). Although the war itself took place from 1991 to 1995, the war duration was extended for 2 years to allow for a post-war effect on the sex ratio, as suggested by Graffelman and Hoekstra (2000). The data on live births during wartime was obtained from the unaffected counties and the unoccupied parts of the affected counties (as data from the occupied territories were not available). The likely decrease in absolute number of births during the war period should not affect the conclusions of the paper, as all our results are expressed as proportions, insensitive to fluctuations in absolute numbers. Male proportions were calculated and used in the analyses (although many papers refer to the sex ratio, the widely used measure is the proportion of males at birth). The odds ratios (OR) of being a male were calculated, and being born in the county affected by warfare considered as the risk factor (Ansari-Lari and Saadat, 2002).
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The analyses at the level of specific counties showed substantial variation. However, a significant increase in the sex ratio was observed only in two counties unaffected by the warfare: Krapina County (pre-war to wartime OR=1.0339, 95% CI 1.00571.0622, wartime to post-war OR=1.0955, 95% CI 1.06471.1262) and Varazdin County (pre-war to wartime OR=0.9647, 95% CI 0.94000.9894, wartime to post-war OR=1.0375, 95% CI 1.01111.10639).
Comparison of affected versus unaffected counties revealed no significant difference (affected: pre-war to wartime OR=1.0040, 95% CI 0.99591.0122, wartime to post-war OR=0.9968, 95% CI 0.98771.0060; unaffected: pre-war to wartime OR=0.9956, 95% CI 0.98921.0019, wartime to post-war OR=1.0085, 95% CI 1.00181.0153) (Figure 1).
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Similar sex ratios in affected and unaffected counties in Croatia, alongside the significant increase observed only in two unaffected counties, suggest that warfare did not cause any detectable increase in the sex ratio in the 19911995 war in Croatia. This is despite 5 years of warfare (long risk exposure), and tens of thousands of casualties, devastation of one-third of the country's infrastructure, and up to 1x106 displaced persons and refugees (high risk intensity) (Labar et al., 2004). Although the duration and intensity of the war in Slovenia (10 days in duration, relatively few casualties, minor damage to infrastructure) were not comparable to the war in Croatia, Zorn et al. (2002)
described a decline in sex ratio at birth after the 10 days of the war in Slovenia, concluding that acute psychological stress caused a decrease in sex ratio from 0.518 in 1991 (pre-war) to 0.504 in 1992 (post-war). The absence of the increase in sex ratio is therefore a common conclusion to both studies, although they used different approaches and methods.
Investigation into the sex ratios of remaining Balkan countries affected by the recent warfare remains to be performed. Should the findings from those countries support the observation of wartime-related stability or decrease of the sex ratio, it could be hypothesized that factors other than exposure to warfare itself caused the observed increase in the sex ratio at birth in previous papers.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Catalano RA (2003) Sex ratios in the two Germanies: a test of economic stress hypothesis. Hum Reprod 18, 19721975.
Fukuda M, Fukuda K, Shimizu T and Moller H (1998) Decline in sex ratio at birth after Kobe earthquake. Hum Reprod 13, 23212322.[Abstract]
Graffelman J and Hoekstra RF (2000) A statistical analysis of the effect of warfare on the human secondary sex ratio. Hum Biol 72, 433445.[ISI][Medline]
Hansen D, Moller H and Olsen J (1999) Severe periconceptional life events and the sex ratio of the offspring: follow up study on five national registers. Br Med J 319, 548549.
James W (1987) The human sex ratio. Part 1: A review of the literature. Hum Biol 59, 721752.[ISI][Medline]
James WH (2003) Sex ratios of births conceived during wartime. Hum Reprod 18, 11331334.
Labar B, Rudan I, Ivankovic D et al. (2004) Haematological malignancies in childhood in Croatia: investigating the theories of depleted uranium, chemical plant damage and population mixing. Eur J Epidemiol 19, 5560.[CrossRef][ISI][Medline]
Zorn B, Sucur V, Stare J and Meden-Vrtovec H (2002) Decline in sex ratio at birth after 10-day war in Slovenia. Hum Reprod 17, 31733177.
Submitted on February 3, 2005; resubmitted on March 29, 2005; accepted on April 22, 2005.
|