Brief Communication Decline in sex ratio at birth after 10-day war in Slovenia

BACKGROUND: We investigated whether the psychological stress related to a short war (26 June–7 July, 1991) in Slovenia induced changes in fertility, sex ratio at birth and semen quality characteristics. METHODS: Sex ratios [i.e. males/(males females)] for 4966 births in the general population of Slovenia and separately for 1565 births in the Slovenian capital, Ljubljana, from January–March 1992 were compared with the sex ratio calculated for the same time period in 1991 and 1993. Semen analyses for 38 normozoospermic men attending an outpatient infertility clinic from May to September 1991 were also evaluated. RESULTS: In the general population in Slovenia there was a significant fall in the sex ratio at birth in 1992, compared with 1991 (0.504 versus 0.518; P 0.03). In Ljubljana, the decline in sex ratio in 1992 was even more pronounced: 0.483 versus 0.537 in 1991 (P 0.0001) and 0.483 versus 0.516 in 1993 (P 0.005). A decrease in the proportion of sperm that were progressively motile from 56% before the war to 52% after it (P 0.01) and of those that were rapidly motile from 40 to 36% (P 0.01) was observed. CONCLUSIONS: Acute psychological stress in relation to a short war in Slovenia resulted 6 to 9 months later in a decrease in the observed sex ratio at birth. Negative changes in sperm motility may be involved in the sex ratio modifications.