Data Collection
Baseline clinical data for cases and controls were obtained through electronic chart review. For all women, the following data were recorded: maternal age, parity, pre-pregnancy height and weight, baseline pre-pregnancy or early pregnancy vital signs (blood pressure, heart rate), anatomic details of cardiovascular disease (study group), cardiac surgical/interventional history, baseline New York Heart Association functional class and medication history. When available, obstetric and labour/delivery information was also collected.