Abstract
This study aims to identify the optimal postnatal weight gain through age 6 to prevent obesity in preterm infants. Nested case-control study using a nationwide South Korean cohort (2008–2015) included preterm infants with obesity (cases) and those with BMI between the 5th–85th percentiles (controls) at age 6. Weight-for-age and BMI z-scores were compared using Cohen’s d. Logistic regression identified obesity risk factors, and net benefit analysis determined optimal intervention points by birth weight. Among 41,286 preterm infants, 3349 (8.1%) developed obesity. Birth weight z-score differences between cohorts were small (Cohen’s d = 0.115), but differences in weight-for-age z-scores emerged at 4–6 months (Cohen’s d = 0.474) and grew over time (3 years: Cohen’s d = 1.278). Risk factors included low gestational age, high birth weight, rural residence, lower socioeconomic status, and recent birth. Higher z-scores correlated with greater net benefit, with extremely low birth weight infants showing earlier increases. In conclusion, a rapid increase in z-scores from 4 to 6 months was strongly linked to obesity at 6 years. Optimal predictive values varied by birth weight, emphasizing the need for early monitoring and tailored cut-off values for z-scores based on corrected age to prevent obesity.
Data availability
This study was based on data from the National Health Claims Database established by the National Health Insurance Service of the Republic of Korea. Applications for using National Health Insurance Service data are reviewed by the Inquiry Committee of Research Support, and if the application is approved, raw data are provided to the applicant for a fee. We cannot provide access to the data, analytical methods, and research materials to other researchers because of the intellectual property rights held by the National Health Insurance Corporation. However, investigators who wish to reproduce our results or replicate the procedure can use the database, which is open for research purposes (https://nhiss.nhis.or.kr/ accessed on July 7, 2023).
References
Chawanpaiboon, S. et al. Global, regional, and National estimates of levels of preterm birth in 2014: a systematic review and modelling analysis. Lancet Glob Health. 7, e37–e46. https://doi.org/10.1016/s2214-109x(18)30451-0 (2019).
Ohuma, E. O. et al. National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis. Lancet 402, 1261–1271. https://doi.org/10.1016/s0140-6736(23)00878-4 (2023).
Ingol, T. T. et al. Underdiagnosis of obesity in pediatric clinical care settings among children born preterm: a retrospective cohort study. Int. J. Obes. (Lond). 45, 1717–1727. https://doi.org/10.1038/s41366-021-00834-1 (2021).
Yitayew, M., Chahin, N., Rustom, S. & Thacker, L. R. Hendricks-Muñoz, K. D. Fenton vs. Intergrowth-21st: postnatal growth assessment and prediction of neurodevelopment in preterm infants. Nutrients https://doi.org/10.3390/nu13082841 (2021).
Agency for Healthcare Research and Quality. Transitioning Newborns from NICU to Home, (2013). https://www.ahrq.gov/patient-safety/settings/hospital/resource/nicu/packet/apb.html
Hui, L. L., Lam, H. S., Leung, G. M. & Schooling, C. M. Late prematurity and adiposity in adolescents: evidence from children of 1997 birth cohort. Obes. (Silver Spring). 23, 2309–2314. https://doi.org/10.1002/oby.21267 (2015).
Vohr, B. R. et al. Extreme preterm infant rates of overweight and obesity at school age in the SUPPORT neuroimaging and neurodevelopmental outcomes cohort. J. Pediatr. 200, 132–139e133. https://doi.org/10.1016/j.jpeds.2018.04.073 (2018).
Su, Y. Y. et al. Long-term effects on growth in preterm and small for gestational age infants: A National birth cohort study. Pediatr. Neonatol. 66, 168–175. https://doi.org/10.1016/j.pedneo.2024.06.007 (2025).
O’Shea, T. M. et al. Association of growth during infancy with neurodevelopment and obesity in children born very preterm: the environmental influences on child health outcomes cohort. J. Pediatr. 271, 114050. https://doi.org/10.1016/j.jpeds.2024.114050 (2024).
O’Shea, T. M. et al. Growth during infancy after extremely preterm birth: Associations with later neurodevelopmental and health outcomes. J. Pediatr. 252, 40–47.e45 (2023). https://doi.org/10.1016/j.jpeds.2022.08.015
Taveras, E. M. et al. Weight status in the first 6 months of life and obesity at 3 years of age. Pediatrics 123, 1177–1183. https://doi.org/10.1542/peds.2008-1149 (2009).
Weng, S. F., Redsell, S. A., Swift, J. A., Yang, M. & Glazebrook, C. P. Systematic review and meta-analyses of risk factors for childhood overweight identifiable during infancy. Arch. Dis. Child. 97, 1019–1026. https://doi.org/10.1136/archdischild-2012-302263 (2012).
Vasylyeva, T. L. et al. Obesity in prematurely born children and adolescents: follow up in pediatric clinic. Nutr. J. 12, 150. https://doi.org/10.1186/1475-2891-12-150 (2013).
Wood, C. T. et al. Antecedents of obesity among children born extremely preterm. Pediatrics https://doi.org/10.1542/peds.2018-0519 (2018).
Jeon, G. W. et al. Preterm infants fed nutrient-enriched formula until 6 months show improved growth and development. Pediatr. Int. 53, 683–688. https://doi.org/10.1111/j.1442-200X.2011.03332.x (2011).
Powell-Wiley, T. M. et al. Obesity and cardiovascular disease: A scientific statement from the American heart association. Circulation 143, e984–e1010. https://doi.org/10.1161/cir.0000000000000973 (2021).
Markopoulou, P., Papanikolaou, E., Analytis, A., Zoumakis, E. & Siahanidou, T. Preterm birth as a risk factor for metabolic syndrome and cardiovascular disease in adult life: A systematic review and Meta-Analysis. J. Pediatr. 210, 69–80e65. https://doi.org/10.1016/j.jpeds.2019.02.041 (2019).
Amadou, C. et al. Long-term health in individuals born preterm or with low birth weight: A cohort study. Pediatr. Res. https://doi.org/10.1038/s41390-024-03346-6 (2024).
Casirati, A. et al. Preterm birth and metabolic implications on later life: A narrative review focused on body composition. Front. Nutr. 9, 978271. https://doi.org/10.3389/fnut.2022.978271 (2022).
Cerasani, J. et al. Human Milk Feeding and Preterm Infants’ Growth and Body Composition: A Literature Review. Nutrients https://doi.org/10.3390/nu12041155 (2020).
World Health Organization. Obesity and overweight, (2024). https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
Centers for Disease Control and Prevention. Definitions: Obesity and Weight Status, (2024). https://www.cdc.gov/nccdphp/dnpao/data-trends-maps/help/npao_dtm/definitions.html
Ong, K. K., Ahmed, M. L., Emmett, P. M., Preece, M. A. & Dunger, D. B. Association between postnatal catch-up growth and obesity in childhood: prospective cohort study. Bmj 320, 967–971. https://doi.org/10.1136/bmj.320.7240.967 (2000).
Park, H. et al. Metabolic complications of obesity in children and adolescents. Clin. Exp. Pediatr. 67, 347–355. https://doi.org/10.3345/cep.2023.00892 (2024).
Cheon, B. K., Bittner, J. M. P. & Pink, A. E. Contributions of subjective status to eating behaviors, obesity, and metabolic health across development. Appetite 204, 107735. https://doi.org/10.1016/j.appet.2024.107735 (2025).
Wood, C. T. et al. Effects of Breastfeeding, formula feeding, and complementary feeding on rapid weight gain in the first year of life. Acad. Pediatr. 21, 288–296. https://doi.org/10.1016/j.acap.2020.09.009 (2021).
Flores-Barrantes, P., Iguacel, I., Iglesia-Altaba, I., Moreno, L. A. & Rodríguez, G. Rapid weight Gain, infant feeding Practices, and subsequent body mass index trajectories: the CALINA study. Nutrients https://doi.org/10.3390/nu12103178 (2020).
Vizzari, G. et al. Postnatal growth of small for gestational age late preterm infants: determinants of catch-up growth. Pediatr. Res. 94, 365–370. https://doi.org/10.1038/s41390-022-02402-3 (2023).
Hwang, I. T. Long-term care, from neonatal period to adulthood, of children born small for gestational age. Clin. Pediatr. Endocrinol. 28, 97–103. https://doi.org/10.1297/cpe.28.97 (2019).
Mericq, V. et al. Long-term metabolic risk among children born premature or small for gestational age. Nat. Rev. Endocrinol. 13, 50–62. https://doi.org/10.1038/nrendo.2016.127 (2017).
Hokken-Koelega, A. C. S. et al. International consensus guideline on small for gestational age: etiology and management from infancy to early adulthood. Endocr. Rev. 44, 539–565. https://doi.org/10.1210/endrev/bnad002 (2023).
Kim, S. et al. Consumption of Sugar-Sweetened beverages before 2 years of age and Attention-Deficit/Hyperactivity disorder. Ann. Nutr. Metab. 80, 276–286. https://doi.org/10.1159/000539458 (2024).
Jeon, G. W. et al. Long-Term mental health outcomes of bronchopulmonary dysplasia in neonates: an 18-Year National cohort study. J. Pediatr. 276, 114341. https://doi.org/10.1016/j.jpeds.2024.114341 (2025).
Yoon, S. A., Lee, M. H. & Chang, Y. S. Impact of time to full enteral feeding on long-term neurodevelopment without mediating by postnatal growth failure in very-low-birth-weight-infants. Sci. Rep. 13, 2990. https://doi.org/10.1038/s41598-023-29646-1 (2023).
Sharma, D., Farahbakhsh, N., Shastri, S. & Sharma, P. Intrauterine growth restriction - part 2. J. Matern Fetal Neonatal Med. 29, 4037–4048. https://doi.org/10.3109/14767058.2016.1154525 (2016).
Aris, I. M., Kleinman, K. P., Belfort, M. B., Kaimal, A. & Oken, E. A 2017 US reference for Singleton birth weight percentiles using obstetric estimates of gestation. Pediatrics https://doi.org/10.1542/peds.2019-0076 (2019).
Rysavy, M. A. et al. An Immature Science: Intensive Care for Infants Born at ≤ 23 Weeks of Gestation. J. Pediatr. 233, 16–25.e11 (2021). https://doi.org/10.1016/j.jpeds.2021.03.006
Kang, S. et al. Growth in exclusively breastfed and Non-exclusively breastfed children: comparisons with WHO child growth standards and Korean National growth charts. J. Korean Med. Sci. 36, e315. https://doi.org/10.3346/jkms.2021.36.e315 (2021).
Kim, J. H. et al. Diverse weaning foods and diet patterns at multiple time points during infancy period and their association with neurodevelopmental outcomes in 6-year-old children. Eur. J. Clin. Nutr. https://doi.org/10.1038/s41430-024-01528-3 (2024).
Han, T. H. et al. Early onset and increasing disparities in neurodevelopmental delays from birth to age 6 in children from low socioeconomic backgrounds. J. Neurodev Disord. 16, 60. https://doi.org/10.1186/s11689-024-09577-2 (2024).
Sullivan, G. M. & Feinn, R. Using effect Size-or why the P value is not enough. J. Grad Med. Educ. 4, 279–282. https://doi.org/10.4300/jgme-d-12-00156.1 (2012).
Vickers, A. J., van Calster, B. & Steyerberg, E. W. A simple, step-by-step guide to interpreting decision curve analysis. Diagn. Progn Res. 3, 18. https://doi.org/10.1186/s41512-019-0064-7 (2019).
Funding
This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (grant number: HR22C1605-C). This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT) (No. RS-2022-NR070174). The funders played no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.
Author information
Authors and Affiliations
Contributions
G.W.J. and M.Y.H. conceptualized and designed the study, designed the data collection instruments, drafted the initial manuscript, and critically reviewed and revised the manuscript.S.L. conceptualized and designed the study, and critically reviewed and revised the manuscript.J.S., E.K.H., J.H.K., M.S.K., and B.H. designed the data collection, collected data, carried out the initial analyses, and critically reviewed and revised the manuscript.All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Jeon, G.W., Shin, J., Ha, E.K. et al. Optimal weight gain to reduce obesity risk in preterm infants in a National cohort study. Sci Rep (2026). https://doi.org/10.1038/s41598-025-34404-6
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-025-34404-6
