This was a retrospective cohort study that was approved by the Research Ethics Committee of Khon Kaen Hospital. The medical and delivery records of all pregnant women who were diagnosed as pre-eclampsia (study group) and the normotension (control group) at Khon Kaen Hospital between January 1st, 2009 and December 31st, 2009 were reviewed. The exclusion criteria included incomplete medical records and pre-eclamptic women who had a hydatidiform mole.