Age and parity as determinants of maternal mortality--impact of their shifting distribution among parturients in Sweden from 1781 to 1980.

The reduction in maternal mortality in Sweden between 1781 and 1980 is analysed with respect to changes in the distribution of age and parity among parturients over this period. Changes in maternal age contributed to almost 3% of the reduction in mortality over the period 1781-1911 and to 5% between 1911 and 1980. From 1965 to 1980, however, about 50% of the reduction in mortality was caused by a decrease in maternal age. Changes in parity have had the opposite effect. Maternal deaths attributable to the risk factors of age and parity increased from 46% during the 19th century to 80% from 1951 to 1980.