Background: Maternal placental syndromes, including the hypertensive disorders of pregnancy and abruption or infarction of the placenta, probably originate from diseased placental vessels. The syndromes arise most often in women who have metabolic risk factors for cardiovascular disease, including obesity, pre-pregnancy hypertension, diabetes mellitus, and dyslipidaemia. Our aim was to assess the risk of premature vascular disease in women who had had a pregnancy affected by maternal placental syndromes. Methods: We did a population-based retrospective cohort study in Ontario, Canada, of 1.03 million women who were free from cardiovascular disease before their first documented delivery. We defined the following as maternal placental syndromes: pre-eclampsia, gestational hypertension, placental abruption, and placental infarction. Our primary endpoint was a composite of cardiovascular disease, defined as hospital admission or revascularisation for coronary artery, cerebrovascular, or peripheral artery disease at least 90 days after the delivery discharge date. Findings: The mean (SD) age of participants was 28.2 (5.5) years at the index delivery, and 75 380 (7%) women were diagnosed with a maternal placental syndrome. The incidence of cardiovascular disease was 500 per million person-years in women who had had a maternal placental syndrome compared with 200 per million in women who had not (adjusted hazard ratio HR 2.0, 95 CI 1.7-2.2). This risk was higher in the combined presence of a maternal placental syndrome and poor fetal growth (3.1, 2.2-4.5) or a maternal placental syndrome and intrauterine fetal death (4.4, 2.4-7.9), relative to neither. Interpretation: The risk of premature cardiovascular disease is higher after a maternal placental syndrome, especially in the presence of fetal compromise. Affected women should have their blood pressure and weight assessed about 6 months postpartum, and a healthy lifestyle should be emphasised. Background: Maternal placental syndromes, including the hypertensive disorders of pregnancy and abruption or infarction of the placenta, probably originate from diseased placental vessels. The syndromes are most often in women who have metabolic risk factors for cardiovascular disease, including obesity, pre-pregnancy hypertension , diabetes mellitus, and dyslipidaemia. Our aim was to assess the risk of premature vascular disease in women who had had a pregnancy affected by maternal placental syndromes. Methods: We did a population-based retrospective cohort study in Ontario, Canada, of 1.03 million women who were free from cardiovascular disease before their first documented delivery. We defined the following as maternal placental syndromes: pre-eclampsia, gestational hypertension, placental abruption, and placental infarction. Our primary endpoint was a composite of cardiovascular disease, defined as hospital admission or revascularisation for coronary artery, cerebrovascular, or pe ripheral artery disease at least 90 days after the delivery discharge date. Findings: The mean (SD) age of participants was 28.2 (5.5) years at the index delivery, and 75 380 (7%) women were diagnosed with maternal placental syndrome. The incidence of cardiovascular disease was 500 per million person-years in women who had had a maternal placental syndrome compared with 200 per million in women who had not (adjusted hazard ratio HR 2.0, 95 CI 1.7-2.2). This risk was higher in the combined presence of a maternal placental syndrome and poor fetal growth (3.1, 2.2-4.5) or a maternal placental syndrome and intrauterine fetal death (4.4, 2.4-7.9), relative to neither. Interpretation: The risk of premature cardiovascular disease is higher after a maternal placental syndrome, especially in the presence of fetal compromise. Affected women should have their blood pressure and weight assess about 6 months postpartum, and a healthy lifestyle should be emphasized.