University of Oulu

Risnes K, Bilsteen JF, Brown P, et al. Mortality Among Young Adults Born Preterm and Early Term in 4 Nordic Nations. JAMA Netw Open. 2021;4(1):e2032779. doi:10.1001/jamanetworkopen.2020.32779

Mortality among young adults born preterm and early term in 4 Nordic nations

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Author: Risnes, Kari1,2; Bilsteen, Josephine Funck3,4; Brown, Paul1;
Organizations: 1Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Science, Norwegian University of Science and Technology, Trondheim, Norway
2Department of Research, Innovation, and Education, Children’s Clinic, St Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
3Department of Paediatrics, Hvidovre University Hospital, Hvidovre, Denmark
4Section of Epidemiology, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
5Department of Public Health Solutions, Finnish Institute for Health and Welfare, Helsinki and Oulu, Finland
6Department of Public Health and Nursing, Faculty of Medicine and Health Science, Norwegian University of Science and Technology, Trondheim, Norway
7Research Unit for Pediatrics, Pediatric Neurology, Pediatric Surgery, Child Psychiatry, Dermatology, Clinical Genetics, Obstetrics and Gynecology, Otorhinolaryngology, and Ophthalmology, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
8Children’s Hospital, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
9Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
10Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region
11Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York
12Seaver Autism Center for Research and Treatment at Mount Sinai, New York, New York
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
Persistent link:
Language: English
Published: American Medical Association, 2021
Publish Date: 2021-04-29


Importance: Adverse long-term outcomes in individuals born before full gestation are not confined to individuals born at extreme gestational ages. Little is known regarding mortality patterns among individuals born in the weeks close to ideal gestation, and the exact causes are not well understood; both of these are crucial for public health, with the potential for modification of risk.

Objective: To examine the risk of all-cause and noncommunicable diseases (NCD) deaths among young adults born preterm and early term.

Design, Setting, and Participants: This multinational population-based cohort study used nationwide birth cohorts from Norway, Sweden, Denmark, and Finland for individuals born between 1967 and 2002. Individuals identified at birth who had not died or emigrated were followed up for mortality from age 15 years to 2017. Analyses were performed from June 2019 to May 2020.

Exposures: Categories of gestational age (ie, moderate preterm birth and earlier [23–33 weeks], late preterm [34–36 weeks], early term [37–38 weeks], full term [39–41 weeks] and post term [42–44 weeks]).

Main Outcomes and Measures: All-cause mortality and cause-specific mortality from NCD, defined as cancer, diabetes, chronic lung disease, and cardiovascular disease (CVD).

Results: A total of 6 263 286 individuals were followed up for mortality from age 15 years. Overall, 339 403 (5.4%) were born preterm, and 3 049 100 (48.7%) were women. Compared with full-term birth, the adjusted hazard ratios (aHRs) for all-cause mortality were 1.44 (95% CI, 1.34–1.55) for moderate preterm birth and earlier; 1.23 (95% CI, 1.18–1.29) for late preterm birth; and 1.12 (95% CI, 1.09–1.15) for early-term birth. The association between gestational age and all-cause mortality were stronger in women than in men (P for interaction = .03). Preterm birth was associated with 2-fold increased risks of death from CVD (aHR, 1.89; 95% CI, 1.45–2.47), diabetes (aHR, 1.98; 95% CI, 1.44–2.73), and chronic lung disease (aHR, 2.28; 95% CI, 1.36–3.82). The main associations were replicated across countries and could not be explained by familial or individual confounding factors.

Conclusions and Relevance: The findings of this study strengthen the evidence of increased risk of death from NCDs in young adults born preterm. Importantly, the increased death risk was found across gestational ages up to the ideal term date and includes the much larger group with early-term birth. Excess mortality associated with shorter gestational age was most pronounced for CVDs, chronic lung disease, and diabetes.

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Series: JAMA network open
ISSN: 2574-3805
ISSN-E: 2574-3805
ISSN-L: 2574-3805
Volume: 4
Issue: 1
Article number: e2032779
DOI: 10.1001/jamanetworkopen.2020.32779
Type of Publication: A1 Journal article – refereed
Field of Science: 3123 Gynaecology and paediatrics
3142 Public health care science, environmental and occupational health
Funding: This project received funding from the European Union Horizon 2020 research and innovation program under grant agreement 733280 Research on Children and Adults Born Preterm (RECAP). The project has also received funding from Academy of Finland (project 315690), Norface DIAL Programme (Project 462-16-040 Premlife), the Foundation for Pediatric Research, the Sigrid Jusélius Foundation, and the Signe and Ane Gyllenberg Foundation.
EU Grant Number: (956454) RecaP - Capture, recycling and societal management of phosphorus in the environment
Copyright information: This is an open access article distributed under the terms of the CC-BY License. © 2021 Risnes K et al. JAMA Network Open.