Recording their BMI\menstrual history\and childbearing history, the investigators would select 300 healthy women in 6 different age groups which are aged 20-24, aged 25-29, aged 30-34, aged35-39, aged 40-44 and aged 45-49, then draw 1-2 ml blood form their peripheral vein (adding EDTA for anti-coagulation). The investigators are going to perform routine examination on the blood samples and detect T\B\NK lymphocyte through flow cytometry (FCM), thus calculating the absolute number of every species of lymphocyte. The investigators make assessment for the cellular immune function of the women during child-bearing period via comparing distinction in percentage and absolute number of every lymphocyte subset among reproductive-age women in different ages.