The research consists of two stages. In the first stage, the mobile application was developed and a pilot application was made with 6 mothers in the testing of the application. For the second stage of the research, all primiparous mothers in Istanbul University Cerrahpaşa Medical Faculty Hospital between September 2021 and August 2022 constituted the population of the research. The sample of the study consisted of primiparous mothers who met the inclusion criteria and volunteered to participate in the study. The sample of the study formed the Experiment and Control group. Primiparous mothers in the experimental group were included in the mobile application-based breastfeeding education program, and the primiparous mothers in the control group were not included in this program and only benefited from the hospital's routine care services (Figure 1.) Power analysis was performed using the G-Power program to determine the number of samples. According to Cohen's effect size coefficients; According to the calculation made by assuming that the evaluations to be made between two independent groups will have a large effect size (d=0.8), when α: 0.05 and 90% power are taken, there should be at least 34 people for each group, considering the losses that may occur during the research process. A total of 80 primiparous mothers, 40 for one group, were planned to be included in the study..

The research consists of two stages. The first stage of the research consists of creating the information content of the mobile application-based breastfeeding education program, developing the application and making the pilot application. In the second stage of the study, primiparous mothers in the experimental group were included in the mobile application-based breastfeeding education program, while the mothers in the control group were not included in any practice other than routine nursing care. Data from mothers in the experimental and control groups were collected on postpartum first day, fourth week, and eighth week.

The first stage of the research Creating the content of the mobile application-based breastfeeding program In the first stage of the research, the content of the mobile application-based breastfeeding program was prepared in line with the literature. Presenting the content of the program on a scientific basis and the measurement and evaluation of education/programs in the world are now stated as an important criterion of evidence-based studies. For this reason, the content of the application was prepared with reference to the current sources of "World Health Organization" and "Ministry of Health". After the content was prepared, the development process of the mobile application was started.

Development of a mobile application-based breastfeeding program The development of the mobile application consists of six main stages: design, development, testing, reporting, maintenance and deployment. Design phase; It consists of evaluating the requirements analysis, considering the User Interface (UI) and user experience (UX) standards, printing the design as Mock-Up and submitting it for approval, and revising it in line with the data notifications. Development phase; development in line with the approved design, interaction via cloud (Cloud) service (Firebase), and development of the application on Cross-Platform as IOS and Android. Development phase; development in line with the approved design, interaction via cloud (Cloud) service (Firebase), and development of the application on Cross-Platform as IOS and Android. Development phase; development in line with the approved design, interaction via cloud (Cloud) service (Firebase), and development of the application on Cross-Platform as IOS and Android. Test phase; It consists of preparing the pilot-test environment, producing the IPA for the IOS version, producing the APK file for Android and conducting development tests. Reporting phase; consists of reporting and sharing the information received from the user. Maintenance phase; In the testing process, it consists of the process of making adjustments and improvements in the application in line with the feedback. The last stage, the distribution stage, is; It consists of obtaining certificates for Android and Apple, preparing necessary images for Android and Apple market environment, obtaining distribution approval by Apple and Android and uploading them to Apple and Android Market. In this direction, first of all, a special logo was designed for the application. Afterwards, the prepared content was integrated into the application. By clicking on the sign up tab at the first login of the application, an e-mail and password were created and the login application was registered, and the next login was made automatically. The information page of the application contained brief information about the application and three pages on the importance of breastfeeding and breast milk. Afterwards, information about the mother's name, baby's name, baby's gender and baby's birth weight was filled and the application was entered. These two screens were reserved for the first entry only. The main screen of the application used to be six screens. These six screens; Breastfeeding, Expressing, Contingencies, Frequently asked questions and my Breastfeeding Log and Breastfeeding diary. Mothers could record the number and duration of breastfeeding, milking status, the baby's height and weight, if it was a measure, the breastfeeding problem and solutions they encountered, on the "Breastfeeding Introduction" tab, and they could follow their breastfeeding status in the "Breastfeeding Diary" tab. In addition, notifications were sent once at the first entry to the application, and then 2-3 times a week to increase the breastfeeding motivation of the mothers.

The notification sent on the first login to the application; "Dear mom, your breastfeeding journey has begun. In this process, you can access the information you need through the application, keep a diary at the breastfeeding entrance and follow the breastfeeding process..."

Making a pilot application With the development of the application, the pilot application was started. Six mothers who met the inclusion criteria were included. The link of the application was sent to Android-operated phones via google drive in order to prevent sharing, and application invitation mail was sent to IOS-operated phones, application registrations were made through the app store, and the application was accessed by entering the code via the "Test Flight" application.

Mothers expressed the progress error on the breastfeeding home page, this technical issue was edited by the mobile application developer. In addition, mothers stated that they can have videos in the application and that receiving notifications will ensure the continuity of breastfeeding login. With these suggestions, the papers were systematized. No video is included in the application as it may negatively affect the usability of the application.

Second phase of the research In the second stage of the study, mothers who met the criteria for inclusion in the sampling were informed about the purpose, content and method of the study, and informed consent was obtained from the mothers who agreed to participate in the study. Following the CONSORT 2017 (Updated Guidelines for Reporting Randomized Parallel Group Studies) report, mothers were randomly assigned to the Experiment and Control groups using a simple random numbers table on https://www.random.org/integers/. Personal Information Form, Breastfeeding Evaluation Scale and Breastfeeding Problems Evaluation Scale were applied to the mothers in the Experimental and Control groups on the first postpartum day. The mobile application was installed on the phones of the mothers in the experimental group and they were informed about the content and use of the application. The control group benefited only from routine nursing care. Infants' Physical Development Monitoring Form, Breastfeeding Monitoring Form, Breastfeeding Problems Evaluation Scale were applied to the mothers in the experimental and control groups in the fourth and eighth weeks postpartum. The baby's weight, height and head circumference, which was included in the Baby's Physical Development Monitoring Form, was measured at the "Family Health Center". Due to the reduction of the difference between the measurements, the babies were asked to be weighed with clean diapers and without clothes. The mothers who had difficulty in filling out the questions online were contacted by the researcher and they were asked to read and answer the questions. In addition, the Mobile Application Evaluation Form was applied to the experimental group in the eighth week.