Previously, we have introduced you to many facts about deafness, but how does the human hearing function develop? What factors have an impact on fetal and neonatal hearing? What is the best way to take care of your baby during pregnancy and childbirth? Here we will tell you step by step. First of all, let’s look at the development of human auditory function. The external auditory canal, outer tympanic membrane epithelium, inner tympanic vagus epithelium and the nervous system, including the eighth pair of cranial nerves and the auditory center, originate from the ectoderm; the middle ear tympanic chamber and eustachian tube epithelium, and the inner tympanic membrane epithelium originate from the endoderm. The bony vagus of the inner ear and the connective tissue of the middle layer of the tympanic membrane are derived from the mesoderm. These differentiations are completed between the third and eighth week of embryonic age. The fetal inner ear vagus and peripheral peripheral auditory receptors complete normal development by the 24th week of gestation, and the auditory conduction pathway is basically established from the 24th week of gestation. The fetal hearing is established and the fetus can hear the mother’s voice. During this period, pregnant mothers should pay attention to avoid noise. The hearing threshold of the fetus is about 40dB from 27 to 29 weeks of gestation and drops to 13.5dB after 42 weeks of gestation, which is close to the adult level. The hearing function continues to mature after birth. Infants 3 to 5 days after birth already have the ability to distinguish the intensity, pitch and rhythm of stimuli, and in January after birth, they can already respond to different sounds such as speech and crying. Perinatal factors affecting hearing: 1. Genetic factors: In hereditary deafness, there can be hearing impairment alone, but also hearing impairment with other systemic developmental abnormalities, i.e. syndromic deafness. 2, congenital malformations: craniofacial malformations combined with hearing impairment are more frequent. 3. Perinatal infections: These include intrauterine and neonatal infections. Viruses that have been more clearly reported to be associated with deafness include rubella, cytomegalovirus, herpesvirus, others such as toxoplasma, syphilis spirochetes, and bacterial-induced septic meningitis and sepsis, all of which can cause deafness. Viral infections causing deafness are associated with cochlear and eighth pair of cranial nerve damage, and bacterial infections causing deafness are associated with eighth pair of cranial nerve damage. 4. Bilirubin encephalopathy and hyperbilirubinemia: typical symptoms are tetanus, oculomotor disorders, hearing impairment and dental enamel hypoplasia. Generally, the disease may develop when bilirubin >20mg/dl, and may also develop in premature infants <15mg/dl. Bilirubin encephalopathy causes hearing impairment, with lesions in the cochlear nucleus and inferior colliculus. Children with hyperbilirubinemia should have their hearing tested regularly even if they do not show encephalopathy. 5, perinatal ischemic-hypoxic disease: hearing damage is mainly in the cochlear nucleus, cochlea and inferior colliculus. The severity is related to the Apgar score and duration of asphyxia, the presence or absence of neurological symptoms during the neonatal period, EEG abnormalities and duration, and the degree of abnormal brainstem auditory evoked potentials (BAEP). 6. Aminoglycosides: The effects on hearing are related to factors such as patient age, blood concentration, daily dosage, drug accumulation, duration of treatment, and family history. The duration of treatment, family history. 7, fetal alcoholism syndrome: there can be four types of hearing impairment: (1) delayed development of hearing function (2) sensory-neural hearing loss (3) conductive hearing impairment due to otitis media (4) central hearing loss 8, low weight, preterm infants 9, other factors: noise; diabetic mother hypoglycemia; maternal hypothyroidism; birth injury, mechanical injury to the head. Strengthen perinatal protection, reduce hearing damage measures 1, with new health standards, to provide maternal and perinatal physiological, psychological and social adaptation of comprehensive protection. 2.Promote planned pregnancy, which can enable the best protection of the embryo in the early stages of pregnancy. 3.For couples with family history of deafness, genetic counseling should be conducted before pregnancy. 4. Expand the scope of prenatal diagnosis, and prenatal diagnosis of deafness genes should be made for fetuses of couples with a family history of deafness; there should be a systematic testing program for infection during pregnancy to facilitate early diagnosis of fetal infection. 5.Reduce the factors affecting fetal and neonatal poor hearing in the perinatal period. 6.Universal access to services for newborn hearing screening, confirmation of hearing abnormalities and treatment. 7.Newborns with risk factors for hearing impairment should be followed up even if they pass hearing screening during the neonatal period, in order to detect delayed hearing impairment. 8.Health education. 9.Intervention treatment for children with hearing impairment should be extended to families in the community.