Nationwide cohort study of eclampsia incidence in Norway 2000 to 2020

Abstract Background There are few recent population-based studies of sufficient size and duration to reliably assess the incidence of eclampsia over time, particularly in relation to changes in clinical practice following large clinical intervention trials. We aimed to investigate the incidence of eclampsia and its temporal trends in Norway from 2000 to 2020. Methods Population-based cohort study using data from the Medical Birth Registry of Norway and Statistics Norway. Cross-tabulations and regression analysis with general linear models were used to evaluate associations and time trends. Time trends were analyzed using three time periods corresponding to updates to national clinical guidelines, with 2000–2007 as the reference. Results Here we show that amongst 1,215,295 women giving birth the overall incidence of eclampsia is 4.8/10,000 births with a 50% decline from 2000–2007 to 2014–2020 (relative risk (RR) 0.50; 95% confidence interval 0.40–0.62). The incidence is 14/10,000 in multiple gestations, with no temporal decline (RR: 1.06; 95% confidence interval 0.46–2.41). Amongst women with eclampsia, the proportion of registered preeclampsia is stable across time periods (64%; 2000–2020). Conclusions This study, comprising 21 years of national obstetric surveillance shows a decline in eclampsia incidence associated with implementation of clinical trial interventions in obstetric guidelines; including a recommendation for magnesium sulfate prophylaxis in 2008, and consideration of delivery from 37 weeks in preeclamptic pregnancies in 2014, potentially illustrating their effectiveness in a national high-income setting. However, the proportion of women with known preeclampsia remained stable, indicating remaining potential to improve care.