Infant and perinatal mortality in Spain 1981-1991: interprovincial variations in Autonomous Communities with extreme economic levels.

The aims of the present study were to describe and compare infant, neonatal, postneonatal and perinatal mortality in aggregates of Spanish Autonomous Communities (AC) with higher and lower income, as well as to describe and compare their respective inequalities among the provinces constituting AC with similar (high or low) and with extreme economic levels, over the period from 1981 to 1991. The coefficient of variation (weighted by the number of births) has been used as the measure of interprovincial inequalities in mortality within each aggregate of AC and time trends in the average mortality rates and in their coefficients of variation have been analyzed using simple linear regression. The results of the study confirmed that the four mortality rates were all higher in the aggregate of AC of lower income than in that of higher income, and have fallen in both in a similar manner. Thus the perinatal mortality rates for the lower and higher income aggregates of AC respectively were 17.3 and 12.5 per 1000 births in 1981, and 8.3 and 6.8 in 1991. The inequality in postneonatal mortality was dominant in the group of AC with a lower economic level whereas geographical inequalities in perinatal mortality predominated in the higher income group. The predominance of interprovincial inequalities in perinatal mortality when all the AC (with extreme economic levels) were considered suggest that economic factors are closely related to perinatal mortality.