In　the　study　of　gestational　hypertension,　most　of　studies　focused　on　whether　a　risk　factor　is　associated　with　gestational　hypertension.　However,　according　to　the　clinical　experience,　it　is　important　to　know　the　effects　of　risk　factors　on　women＇s　blood　pressure　during　pregnancy.　Thus,　we　examined　the　effects　of　known　risk　factors　(age,　hematocrit,　etc.)　over　gestational　age.　We　also　examined　whether　the　effects　of　known　risk　factors　are　different　between　gestational　hypertension　group　and　preeclampsia　group.　These　were　studied　in　412　pregnant　women　including　1874　clinical　follow-up　records.　On　the　longitudinal　clinical　data　of　pregnant　women,　varying　coefficient　models　were　applied　to　study　the　effects　of　known　risk　factors　over　gestational　age.　The　results　showed　that　the　effects　of　known　risk　factors　varied　with　gestational　age,　and　the　changing　processes　of　known　risk　factors　over　gestational　age　were　different　between　gestational　hypertension　group　and　preeclampsia　group.　In　final,　we　used　the　relative　error　as　the　criterion　to　assess　the　accuracy　of　the　estimated　varying　coefficient　model.　The　relative　errors　for　total　clinical　data,　gestational　hypertension　group　and　preeclampsia　group　were　13.3%,　8.1%　and　14.3%,　respectively.