The uterus is one of the female internal reproductive organs, with thick walls and a small cavity, divided into the body of the uterus and the cervix. It is a muscular organ that nurtures embryos, fetuses and produces menstruation. The size of the uterus can change with different physiological stages of women, and its normal size range is as follows: 1. In adults who are not pregnant, the uterus is slightly flattened in front and behind, inverted pear-shaped, weighing about 50-70g, about 7-9cm long, about 4cm wide, about 2-3cm thick, with a capacity of about 5ml; 2. During pregnancy, with the progress of pregnancy, the formation and development of the fetus, placenta and amniotic fluid, the body of the uterus gradually increases in size and becomes softer to At full term, the volume of the uterus can reach 35cm×25cm×22cm, with a volume of about 5000ml, which is 500-1000 times higher than that of non-pregnancy. In early pregnancy, the uterus is slightly spherical and asymmetrical, and the uterine wall at the site of fertilized egg implantation is clearly prominent. After 12 weeks of gestation, the uterus gradually enlarges beyond the pelvic cavity and can be palpated above the pubic symphysis. In late gestation, the uterus is mildly right-sided, which is associated with the sigmoid colon occupying the left side of the pelvis; 3. In postmenopausal women, the uterus gradually shrinks and all diameters are reduced accordingly. The ratio of the uterine body to the cervix is 1:2 in infancy, 1:1 in adolescence, 2:1 in childbearing years, and over time, becomes 1:1 again after menopause.