A Decrease in Sex Ratio at Birth Nine Months after the Earthquake in L'Aquila

. Multiple factors influence the secondary sex ratio (SSR) including stress, which appears to affect mainly the males born. Objective . We evaluate the effects of the earthquake in L'Aquila on the SSR. Materials and Methods . The SSR for the first six months of 2010 was compared to that of the same period of 2008. The chi-square test and Fisher's test were used for the statistical analysis. Results . Nine months after the earthquake, an important reduction in the SSR was recorded: January 2010 versus January 2008 =0.62 versus 0.96. An overall fall in the SSR was also recorded when the first 3 months of 2010 were compared to the first three months of 2008: 0,82 versus 1,11. When the first three months of 2010 were compared with the second three months of 2010, a statistically significant increase of the sex ratio at birth was noted (0,82 versus 1,27).