Jeong-Seon Lee1,21, Jae Il Shin2,21, Sunyeup Kim3,21, Yong-Sung Choi4,21, Youn Ho Shin5, Jimin Hwang6, Jung U Shin7, Ai Koyanagi8, Louis Jacob8,9, Lee Smith10, Han Eol Jeong11, Yunha Noh11,12,13, In-Sun Oh11,12,13, Sang Youl Rhee14, Chanyang Min14, Seong Ho Cho15, Steve Turner16, Guillaume Fond17, Laurent Boyer17, Dong In Suh18, Krishna Prasad Acharya19, Ju-Young Shin11,20,22 , Seung Won Lee3,22 & Dong Keon Yon4,14,22
1Department of Pediatrics, Soonchunhyang University Bucheon Hospital, Soonchunhyang University School of Medicine, Bucheon, Republic of Korea.
2Department of Pediatrics, Yonsei University College of Medicine, Seoul, Republic of Korea.
3Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea.
4Department of Pediatrics, Kyung Hee University Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea.
5Department of Pediatrics, The Catholic University of Korea, Yeouido St. Mary’s Hospital, Seoul, Republic of Korea.
6Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
7Department of Dermatology, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea.
8Research and Development Unit, Parc Sanitari Sant Joan de Déu, CIBERSAM, ISCIII, Barcelona, Spain.
9Department of Physical Medicine and Rehabilitation, Lariboisière-Fernand Widal Hospital, AP-HP, Université Paris Cité, Paris, France.
10Centre for Health, Performance and Wellbeing, Anglia Ruskin University, Cambridge, UK.
11School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea.
12Deparments of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada.
13Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montreal, Canada.
14Center for Digital Health, Medical Science Research Institute, Kyung Hee University Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea.
15Division of Allergy-Immunology, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
16Maternity and Child Health Division, NHS Grampian, Aberdeen, UK.
17CEReSS-Health Service Research and Quality of Life Center, Assistance Publique-Hopitaux de Marseille, Aix-Marseille University, Marseille, France.
18Department of Pediatrics, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
19Animal Quarantine Office Kathmandu, Budhanilkantha, Kathmandu, Nepal.
20Department of Biohealth Regulatory Science, Sungkyunkwan University, Suwon, Republic of Korea.
21These authors contributed equally: Jeong-Seon Lee, Jae Il Shin, Sunyeup Kim, Yong-Sung Choi.
22These authors jointly supervised this work: Ju-Young Shin, Seung Won Lee, Dong Keon Yon.
Corresponding authors : Correspondence to Ju-Young Shin, Seung Won Lee or Dong Keon Yon.
Benefits of breastfeeding for both the mother and the child are well established, but a comprehensive and robust study to investigate the protective effect of breastfeeding and attenuated time effect stratified by cause of morbidity are lacking. This study is based on the nationwide birth cohort in Korea that includes data on all infants born from 2009 to 2015. Of 1,608,540 children, the median follow-up period was 8.41 years (interquartile range, 6.76-10.06). When compared to children with fully formula feeding, the hospital admission rate was 12% lower in those with partially breastfeeding and 15% lower in those with exclusive breastfeeding. The apparent protective effect of breastfeeding was reduced with increasing age. Our study provides potential evidence of the beneficial association of breastfeeding on subsequent hospital admissions. The protective effect declined over time as the children grew older. Encouraging any breastfeeding for at least the first 6 months among infants is an important public health strategy to improve overall child health.