The development of the fetal ear begins fairly early, at 6 weeks of gestational age, and by the end of the second trimester, the outer, middle, and inner ears have taken shape and formed their basic morphological structures. The development of the auricle, auricular cavity and external auditory canal is mainly derived from the first gill arch, and abnormalities in the development of the first and second gill arches and the first gill sulcus during the embryonic period can lead to malformations of the external and middle ears. The causes of congenital external and middle ear malformations are still being researched and explored, and it is difficult to attribute them to a single genetic or environmental factor. Many parents often feel guilty when their baby has a microtia and feel that it is their own fault. In fact, most cases of microtia are epidemic and there is no family history of the condition. The cause of microtia is still inconclusive, so parents of these children do not need to blame themselves. The occurrence of microtia in newborns can be caused by a variety of risk factors, such as the mother-to-be’s use of prenatal abortion medication during pregnancy, or the use of anti-flu or antibiotic drugs, retinoids, etc.; the mother-to-be’s long-term exposure to toxic chemical corrosives or radiation during pregnancy; the mother’s multiple births or advanced maternal age, or diabetes, or living in a high-altitude area; the fetus’ low birth weight, etc. Low birth weight, etc. These factors may interfere with the normal development of the fetal ear and may cause microtia, as the fetal ear develops early, often in the late second trimester. Mothers-to-be are advised to stay away from these risk factors during pregnancy to reduce the risk of microtia in their babies.