A 30-years-old primipara, 37 gestational weeks, edema legs one week, headache 12 hours, without nausea and vomiting. Examination: BP 160/100mmHg, edema legs+++, urine protein+, hyaline cast 0-2/HP. Which of the following is not the precipitating factor of the disease? A、seasonal variation B、smoking C、Chronic hypertension D、anemia E、dumpy figure