Hair coloring is generally not recommended during pregnancy to avoid harmful substances from entering the body and affecting the development of the fetus. There are more types of hair dyes, and many hair coloring preparations contain substances that are toxic and harmful to the human body. If you dye your hair frequently, the harmful substances in the hair dye may enter your body and be detrimental to your health. Women’s pregnancy is a special physiological period, and it is generally not recommended that women dye their hair during pregnancy. Hair dyes contain chemicals and heavy metals that may enter the capillaries along the hair follicles and enter the mother’s body during the dyeing process, and may affect the fetus through the placenta. To summarize, women are not recommended to dye their hair during pregnancy to avoid affecting the growth or development of the fetus.