A total of 64 preterm infants born before 37 weeks of gestation and their mothers were randomly assigned to the experimental and control groups. The intervention used in the experimental group involved an audio recording with repeated clips of the mother reading a children's book, edited to a duration of 13 minutes. The research commenced on the fourth day after the birth of the research subjects, in which the maternal voice recording was played to infants during heel lance procedure once a day for 3 consecutive days. The infants in the control group received general routine care during heel lance procedure. Physiological indicators, including heart rate, respiratory rate, oxygen saturation, and pain response assessed using the Neonatal Infants Pain Scale (NIPS), were recorded 3 minutes before, during, and at the first and 10th minute after heel lance procedure. From the fourth to the sixth day after birth, video recordings of the research process were made and sent to the mother for viewing. On the seventh day after birth, the effectiveness of mother-infant bonding was evaluated using the Mother-Infant Bonding Inventory (MIBI).

This study is a quantitative study, using Experimental Research Design, using G*Power 3.1 to estimate the number of samples, the sample size is 62. There aren't rule out the possibility of congenital hearing loss. According to the literature, the prevalence of deafness in premature or low-weight newborns is about 1-2%. Therefore, the number of samples will increase by 2 according to the prevalence of deafness. After the completion of the case, the hearing screening of the subjects will be continuously tracked to avoid the final loss of samples. Therefore, the total number of cases is 64. In this study, the allocation concealment principle was applied. Before the distribution, the main caregivers and researchers did not know the distribution rules and the distribution results. The sampling method of randomized control trial stratified block randomization was adopted. According to the past clinical birth rate, the number of weeks of pregnancy was less than 31+6 weeks. The proportion of newborns born from 32 weeks to 36+6 weeks of gestational weeks is about 1:2, respectively. Finally, the experimental group and the control group were randomly assigned in this way. There are 20 infants in less than 31+6 weeks group, 44 infants in more than 31+6 weeks group.

The process of receiving the case was the evening of the 4th day after the birth of the study subjects. The premature infants of the experimental group began to listen the maternal voice 3 minutes before the heel lance procedure until the end of the blood collection for 13 minutes, Heart rate (HR), respiratory rate (RR), oxygen saturation (%, OSPR), and pain which evaluated by Neonatal Infants Pain Scale (NIPS) were recorded 3 minutes before, during,and at the first and 10th minutes after heel lance procedure. The monitoring was continued for 3 days.

The study was conducted for three consecutive days from the fourth day after the birth of the subject. The three-day experimental group and the control group were recorded by the camera, uploaded to YouTube within 24 hours after recording, and the film was used for three consecutive days using a private link. Confirm that the mother has watched this video.and please ask the mother to fill out the mother-infant bonding questionnaire.

Inclusion Criteria:

• 1.Babies born alive before 37 weeks of pregnancy 2.Infant was singlet 3.Infants who were required to receive heel lance procedure every 8 hours after physicians' diagnoses 4.Infants' primary caregivers who could read Chinese that agreed to participate in this study and sign written consent forms

Exclusion Criteria:

• 1.Infants with congenital anomaly, congenital or postnatal sepsis, or brain injury 2.Infants' mother smoked, drunk or illegally used drugs while she was pregnant