Why is it dangerous to X-ray a human fetus?

A human fetus is still early in the stages of development and if hit with X-rays can cause damage or defects in the fetus' body. The radiation could cause many problems within individual cells, including the damaging of receptor proteins which could cause cancerous tumors to grow. A human fetus, or any other fetus, is more susceptible to radiation damage because many of their cells are still stem cells (cells that can continue to divide endlessly and haven't been defined as a certain cell). In other Words these cells aren't specified yet, they could become skin cells or stomach cells so radiation could mutate them and since they can divide easily the defect could easily spread.