OBJECTIVE:To test the hypothesis that a longer length of time between diagnosis of hypertensive disorders of pregnancy and delivery is associated with increased risk of cardiovascular morbidity in the years after delivery.METHODS:This is a retrospective cohort study based in the New York State Inpatient Database. The first delivery for all patients from 2005 to 2014 who delivered preterm with an International Classification of Diseases, 9th Revision, Clinical Modification code for hypertensive disorders of pregnancy (excluding isolated chronic hypertension) was included. The duration between diagnosis and delivery was divided into 7 days or less or more than 7 days. The primary outcome was admission for a composite of cardiovascular disease, stroke, or death after the index delivery through December 31, 2014.RESULTS:There were 22,594 patients with a median follow-up period of 5.2 years: 19,750 (87.4%) were delivered within 7 days of diagnosis and 2,844 (12.6%) were delivered more than 7 days from diagnosis. The primary outcome occurred in 216 (1.1%) patients in the 0-7 days group (21 events/10,000 person-years) and 67 (2.4%) patients in the more than 7 days group (46 events/10,000 person-years), adjusted hazard ratio 1.45 (95% CI 1.09 to 1.93). The findings were robust in a number of sensitivity analyses.CONCLUSIONS:Prolonged expectant management of preterm hypertensive disorders of pregnancy is associated with an increased risk of maternal cardiac disease in the ensuing years.