Objective: To determine changes in the incidence and pattern of eclampsia within the same geographical area over a 60-year period.
Design: A retrospective, descriptive study of 1259 consecutive women classified, at the time, as having had an eclamptic convulsion between the years 1931 and 1990.
Setting: A large city centre teaching hospital and the surrounding catchment area.
Main outcome measures: The changes in the incidence and timing of the convulsion and the outcomes for the mother and baby.
Results: Over the study period, the incidence of eclampsia fell by more than 90%, from 74.1/10,000 in the 1930s to 7.2/10,000 in the 1980s. Most of the reduction occurred over the first four decades, with little change in the last 20 years. Overall, 44% of the cases of eclampsia occurred in the antenatal period, 33% intrapartum and 23% postpartum. Since the biggest decreases were seen in the incidence of antenatal and particularly intrapartum eclampsia, there has been a relative increase in the proportion of eclampsia occurring postpartum. Maternal death from eclampsia occurred in 15.1% of cases between 1931 and 1940, 13.4% between 1941 and 1950, but fell dramatically to < or = 3.9% after 1950. There has been no maternal death since 1964. Apart from the first decade, postpartum eclampsia was associated with significantly less risk of death to the mother throughout the study period. Perinatal death rate has fallen steadily from 432.6/1000 cases of eclampsia between 1931 and 1940 over the first three decades, to 168.7/1000 between 1961 and 1970. There has been little change since, although a lower proportion of neonatal deaths occurred as stillbirths.
Conclusions: We found a significant reduction in both the incidence of eclampsia and associated morbidity in this population over the last 60 years. This has occurred in association with the introduction of the National Health Service, widespread antenatal care for all and a general improvement in health and welfare. Any further reduction in the incidence in the UK may be difficult to achieve. Since the incidence of eclampsia is now low, efforts should perhaps be directed at minimising the morbidity associated with severe pre-eclampsia rather than prevention of convulsions.