Heterogeneous effects of natural selection on the Italian newborns.

We have studied the impact of natural selection through stillbirth on the Italian population, taking into account the socio-economic heterogeneity of the country. The results suggest that older age at delivery and lower cultural level of the mothers, indicators of critical biological and socio-economic conditions, even at present increase stillbirth risk. Moreover, in the less favourable environment of the southern regions, selection is still sex-specific.