The first month of pregnancy, dyed hair hazards are the following aspects: the first aspect, may cause harm to pregnant women, because most of the hair dyes are chemical products, may be through the skin mucous membrane of the scalp, infiltration to the head of the blood vessels and then reach the whole body inside the blood vessels, and then reach all parts of the human body, it may lead to infections, and even allergies and other common adverse reactions. The most likely cause pregnant women head skin allergic reactions, such as red bumps or hair loss. The second aspect is that it may cause harm to the fetus, because in the first month of pregnancy, the fetus is in a sensitive period of development, and hair dyes are basically chemical ingredients, which may indirectly reach the fetus through the blood circulation of the pregnant woman, and cause adverse effects on the fetus’s nervous system, as well as the digestive system, and so on.