The combined effects of preterm delivery, small-for-gestational-age offspring, hypertensive disorders of pregnancy, placental abruption and stillbirth on early maternal death from cardiovascular causes have not previously been described in a large cohort. We investigated the effects of pregnancy complications on early maternal death in a registry-based retrospective cohort study of 782 287 women with a first singleton delivery in Denmark 1978-2007, followed for a median of 14.8 years (range 0.25-30.2) accruing 11.6 million person-years. We employed Cox proportional hazard models of early death from cardiovascular and non-cardiovascular causes following preterm delivery, small-for-gestational-age offspring and hypertensive disorders of pregnancy. We found that preterm delivery and small-for-gestational-age were both associated with subsequent death of mothers from cardiovascular and non-cardiovascular causes. Severe pre-eclampsia was associated with death from cardiovascular causes only. There was a less than additive effect on cardiovascular mortality hazard ratios with increasing number of pregnancy complications: preterm delivery 1.90 [95% confidence intervals 1.49, 2.43]; preterm delivery and small-for-gestational-age offspring 3.30 [2.25, 4.84]; preterm delivery, small-for-gestational-age offspring and pre-eclampsia 3.85 [2.07, 7.19]. Thus, we conclude that, separately and combined, preterm delivery and small-for-gestational-age are strong markers of early maternal death from both cardiovascular and non-cardiovascular causes, while hypertensive disorders of pregnancy are markers of early death of mothers from cardiovascular causes.