Pregnancy complications such as preeclampsia and preterm birth are known to affect infant health, but their influence on mothers’ long-term health is not well understood. Most previous studies are seriously limited by their reliance on information from the first pregnancy. Often they lack the data to study women’s complete reproductive histories. Without a complete reproductive history, the relationship between pregnancy complications and women’s long-term health cannot be reliably studied. The Medical Birth Registry of Norway, covering all births from 1967-, includes information on more than 3 million births and 1.5 million sibships. Linking this to population based death and cancer registries provides a worldwide unique source of population-based data which can be analysed to identify heterogeneities in risk by lifetime parity and the cumulative experience of pregnancy complications. Having worked in this field of research for many years, I see many erroneous conclusions in studies based on insufficient data. For instance, both after preeclampsia and after a stillbirth, the high risk of heart disease observed in one-child mothers is strongly attenuated in women with subsequent pregnancies. I will study different patterns of pregnancy complications that occur alone or in combination across pregnancies, and analyse their associations with cause specific maternal mortality. Using this unique methodology, I will challenge the idea that placental dysfunction is the origin of preeclampsia and test the hypothesis that pregnancy complications may cause direct long-term effects on maternal health. The findings of this research have the potential to advance our understanding of how pregnancy complications affect the long-term maternal health and help to develop more effective chronic disease prevention strategies.