It is also dangerous for pregnant women to dye their hair without dyeing the roots, because the smell emitted by some hair dyes may cause irritation to the human body and affect the fetus. Most of the hair dyes used in hair coloring contain aromatic chemicals, which are volatile and can enter the mother’s bloodstream through the respiratory tract and then enter the fetus through the placenta, causing malformations, miscarriages and premature births. Therefore, if a pregnant woman dyes her hair, even if she doesn’t dye the roots of her hair, it may be dangerous to the fetus. Especially in the first three months, the fetus is in the process of development of various organs and systems, if exposed to toxic and harmful substances during this period, it may cause fetal malformation in the future. Pregnant women should pay attention to the health care during pregnancy, eat more food rich in protein, eat more fresh vegetables and fruits, ensure that the food intake is balanced, and avoid exposure to toxic and harmful substances. If a pregnant woman has already dyed her hair during pregnancy, then she needs to keep an eye on the fetus, go to the maternity checkups on time, and seek medical attention if necessary.