There are several reasons for knee soreness in pre-pregnancy: first, it may be a normal physiological reaction, because the hormone levels in a woman’s body in pre-pregnancy have changed more significantly, such as estrogen, sex hormones, thyroid hormones or calcitonin, and so on, and the changes in the levels of all these hormones will have a significant impact on the bones, muscles, and metabolism of the whole body. As the knee’s response to these hormones is relatively sensitive and strong, knee soreness will occur. Secondly, it may be calcium deficiency, which is also a reason that some women have decreased calcium ion levels in the blood due to physiological changes. If a woman is deficient in calcium, it will cause the normal growth and development of bones as well as the division and proliferation of skeletal muscle cells to be impaired, and osteoporosis or malformation of bone differentiation will occur, which can also cause knee pain.