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Cited by 49Infant Development and Preterm CareMaternal and Neonatal HealthcarePreterm Birth and Chorioamnionitis

Short-Term and Long-Term Mortality Risk After Preterm Birth

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Ahmed, Asma M., Grandi, Sonia M., Pullenayegum, Eleanor, McDonald, Sarah D., Beltempo, Marc, Premji, Shahirose S., Pole, Jason D., Bacchini, Fabiana +2 more·2024·JAMA Network Open
DOI 10.1001/jamanetworkopen.2024.45871PMC PMC11579792
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Abstract

Importance: Preterm birth (PTB) is a leading cause of neonatal mortality. However, evidence on mortality beyond the neonatal period is limited, especially in North America. Objective: To examine associations of PTB with all-cause and cause-specific mortality from birth through 23 to 36 years of age. Design, Setting, and Participants: This population-based matched cohort study of live births in Canada included individuals born between January 1, 1983, and December 31, 1996, and followed up until December 31, 2019. Data were analyzed from June 1, 2023, to April 30, 2024. Exposure: PTBs, between 24 and 37 weeks’ gestation (with gestational age [GA]-specific subcategories of 24 to 27 weeks, 28 to 31 weeks, 32 to 33 weeks, and 34 to 36 weeks) compared with term births (37-41 weeks’ gestation). Main Outcomes and Measures: All-cause mortality and cause-specific mortality were the main outcomes. Risk differences (RDs) and risk ratios (RRs) were estimated for all-cause mortality using log-binomial regressions and hazard ratios were estimated for cause-specific mortality using Cox proportional hazards regression models (censoring individuals who died from other causes) within prespecified age intervals (ages 0-11 months and ages 1-5, 6-12, 13-17, 18-28, and 29-36 years). Observed confounding was accounted for using coarsened exact matching on baseline characteristics. Results: Of 4 998 560 births (54.2% male), 6.9% were born preterm (with GA-specific subcategories of 0.3% born at 24-27 weeks, 0.6% at 28-31 weeks, 0.8% at 32-33 weeks, and 5.1% at 34-36 weeks). During a median of 29 years of follow-up, 72 662 individuals died (14 312 born preterm and 58 350 at term). PTB was associated with an increased risk of death in all age intervals, with the highest RDs and RRs from birth through infancy (ages 0-11 months) (RD, 2.29% [95% CI, 2.23%-2.35%]; RR, 11.61 [95% CI, 11.09-12.15]) and in early childhood (ages 1-5 years) (RD, 0.34% [95% CI, 0.31%-0.36%]; RR, 2.79 [95% CI, 2.61-2.98]) and the lowest RDs and RRs among those between ages 18 and 28 years (RD, 0.07% [95% CI, 0.04%-0.10%]; RR, 1.13 [95% CI, 1.07-1.19]). We identified increased risks of mortality associated with several causes, including respiratory, circulatory, and digestive system disorders; nervous system, endocrine, and infectious diseases; cancers; congenital malformations; and conditions originating in the perinatal period. No associations were found for external causes of deaths. Associations by GA categories suggested lower risks with higher GA. Conclusions and Relevance: The findings of this population-based matched cohort study suggest that individuals born preterm were at an increased risk of death from birth until their third and fourth decades of life, with higher risks as GA decreased. Some of these associations may have been partly due to underlying health determinants that affected PTB and mortality. These findings suggest that PTB should be recognized as a risk factor for mortality and could inform preventive strategies.

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  • Preterm birth and FGR are clinically observable sentinel phenotypes that may reflect several adverse maternal-placental-fetal pathways and are themselves associated with long-term cardiometabolic risk.

    “Preterm birth and FGR are clinically observable sentinel phenotypes that may reflect several adverse maternal–placental–fetal pathways and are themselves associated with long-term cardiometabolic risk [97,98,99,100,101].”

    From Placental Pathophysiology and Developmental Programming of Adult Cardiometabolic Risk: A Narrative Review of Pregnancy Exposures (2026) · cites this paper as [97]

    The Discussion (page unavailable) associates preterm birth with later adiposity, cardiometabolic complications, diabetes, heart disease, and hypertension. It does not establish the same long-term risk for fetal growth restriction (FGR) or characterize preterm birth and FGR together as sentinel phenotypes reflecting maternal–placental–fetal pathways. Its discussion of fetal growth concerns how it contributes to low birth weight, not FGR's claimed role or risk. (LLM, conf=0.86)

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  1. [1]Perin J, Mulick A, Yeung D,. Global, regional, and national causes of under-5 mortality in 2000-19: an updated systematic analysis with implications for the Sustainable Development goals. Lancet Child Adolesc Health. 2022; 6(2): 106- 115. doi: 10.1016/S2352-4642(21)00311-4 34800370 PMC8786667 · DOI · Paper page
  2. [2]Ohuma EO, Moller AB, Bradley E,. National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis. Lancet. 2023; 402(10409): 1261- 1271. doi: 10.1016/S0140-6736(23)00878-4 37805217 · DOI
  3. [3]Blencowe H, Cousens S, Oestergaard MZ,. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. Lancet. 2012; 379(9832): 2162- 2172. doi: 10.1016/S0140-6736(12)60820-4 22682464 · DOI · Paper page
  4. [4]Goldenberg RL, Culhane JF, Iams JD, Romero R. Epidemiology and causes of preterm birth. Lancet. 2008; 371(9606): 75- 84. doi: 10.1016/S0140-6736(08)60074-4 18177778 PMC7134569 · DOI · Paper page
  5. [5]Saigal S, Doyle LW. An overview of mortality and sequelae of preterm birth from infancy to adulthood. Lancet. 2008; 371(9608): 261- 269. doi: 10.1016/S0140-6736(08)60136-1 18207020 · DOI · Paper page
  6. [7]Patel RM. Short-and long-term outcomes for extremely preterm infants. Am J Perinatol. 2016; 33(3): 318- 328. doi: 10.1055/s-0035-1571202 26799967 PMC4760862 · DOI
  7. [8]Matthews TJ, MacDorman MF, Thoma ME. Infant mortality statistics from the 2013 period linked birth/infant death data set. Natl Vital Stat Rep. 2015; 64(9): 1- 30. 26270610
  8. [9]Risnes KR, Pape K, Bjørngaard JH, Moster D, Bracken MB, Romundstad PR. Premature adult death in individuals born preterm: a sibling comparison in a prospective nationwide follow-up study. PLoS One. 2016; 11(11): e0165051. doi: 10.1371/journal.pone.0165051 27820819 PMC5098830 · DOI
  9. [10]Crump C. Preterm birth and mortality in adulthood: a systematic review. J Perinatol. 2020; 40(6): 833- 843. doi: 10.1038/s41372-019-0563-y 31767981 PMC7246174 · DOI
  10. [11]Crump C, Sundquist J, Winkleby MA, Sundquist K. Gestational age at birth and mortality from infancy into mid-adulthood: a national cohort study. Lancet Child Adolesc Health. 2019; 3(6): 408- 417. doi: 10.1016/S2352-4642(19)30108-7 30956154 PMC6691360 · DOI
  11. [12]Crump C, Sundquist K, Sundquist J, Winkleby MA. Gestational age at birth and mortality in young adulthood. JAMA. 2011; 306(11): 1233- 1240. doi: 10.1001/jama.2011.1331 21934056 · DOI
  12. [13]Risnes K, Bilsteen JF, Brown P,. 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 33416885 PMC7794670 · DOI · Paper page
  13. [14]Srinivasjois R, Nembhard W, Wong K, Bourke J, Pereira G, Leonard H. Risk of mortality into adulthood according to gestational age at birth. J Pediatr. 2017; 190: 185- 191.e1. doi: 10.1016/j.jpeds.2017.07.051 29144243 · DOI
  14. [15]Swamy GK, Ostbye T, Skjaerven R. Association of preterm birth with long-term survival, reproduction, and next-generation preterm birth. JAMA. 2008; 299(12): 1429- 1436. doi: 10.1001/jama.299.12.1429 18364485 · DOI
  15. [16]Patel RM, Kandefer S, Walsh MC,; Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Causes and timing of death in extremely premature infants from 2000 through 2011. N Engl J Med. 2015; 372(4): 331- 340. doi: 10.1056/NEJMoa1403489 25607427 PMC4349362 · DOI
  16. [17]Ancel PY, Goffinet F, Kuhn P,; EPIPAGE-2 Writing Group. Survival and morbidity of preterm children born at 22 through 34 weeks’ gestation in France in 2011: results of the EPIPAGE-2 cohort study. JAMA Pediatr. 2015; 169(3): 230- 238. doi: 10.1001/jamapediatrics.2014.3351 25621457 · DOI
  17. [18]Fellman V, Hellström-Westas L, Norman M,. One-year survival of extremely preterm infants after active perinatal care in Sweden. Obstetric Anesthesia Digest. 2010; 30(1): 22- 23. doi: 10.1097/01.aoa.0000367003.25266.35 19491184 · DOI
  18. [20]Joseph KS, Kramer MS, Allen AC, Mery LS, Platt RW, Wen SW. Implausible birth weight for gestational age. Am J Epidemiol. 2001; 153(2): 110- 113. doi: 10.1093/aje/153.2.110 11159154 · DOI
  19. [21]Fell DB, Park AL, Sprague AE, Islam N, Ray JG. A new record linkage for assessing infant mortality rates in Ontario, Canada. Can J Public Health. 2020; 111(2): 278- 285. doi: 10.17269/s41997-019-00265-6 31858437 PMC7109219 · DOI
  20. [25]Grandi SM, Hinkle SN, Mumford SL,. Long-term mortality in women with pregnancy loss and modification by race/ethnicity. Am J Epidemiol. 2022; 191(5): 787- 799. doi: 10.1093/aje/kwac023 35136903 PMC9630116 · DOI
  21. [26]Tjepkema M, Wilkins R, Long A. Cause-specific mortality by income adequacy in Canada: A 16-year follow-up study. Health Rep. 2013; 24(7): 14- 22. 24258280
  22. [28]Iacus SM, King G, Porro G. Causal inference without balance checking: coarsened exact matching. Polit Anal. 2012; 20(1): 1- 24. doi: 10.1093/pan/mpr013 · DOI · Paper page
  23. [30]Ahmed AM, Pullenayegum E, McDonald SD,. Preterm birth, family income, and intergenerational income mobility. JAMA Netw Open. 2024; 7(6): e2415921. doi: 10.1001/jamanetworkopen.2024.15921 38857046 PMC11165381 · DOI
  24. [31]Gough A, Spence D, Linden M, Halliday HL, McGarvey LPA. General and respiratory health outcomes in adult survivors of bronchopulmonary dysplasia: a systematic review. Chest. 2012; 141(6): 1554- 1567. doi: 10.1378/chest.11-1306 22116801 · DOI
  25. [32]Nagiub M, Kanaan U, Simon D, Guglani L. Risk factors for development of pulmonary hypertension in infants with bronchopulmonary dysplasia: systematic review and meta-analysis. Paediatr Respir Rev. 2017; 23: 27- 32. doi: 10.1016/j.prrv.2016.11.003 28188008 · DOI
  26. [33]O’Reilly M, Sozo F, Harding R. Impact of preterm birth and bronchopulmonary dysplasia on the developing lung: long-term consequences for respiratory health. Clin Exp Pharmacol Physiol. 2013; 40(11): 765- 773. doi: 10.1111/1440-1681.12068 23414429 · DOI
  27. [34]Bazacliu C, Neu J. Necrotizing enterocolitis: long term complications. Curr Pediatr Rev. 2019; 15(2): 115- 124. doi: 10.2174/1573396315666190312093119 30864508 · DOI
  28. [35]Jones IH, Hall NJ. Contemporary outcomes for infants with necrotizing enterocolitis—a systematic review. J Pediatr. 2020; 220: 86- 92.e3. doi: 10.1016/j.jpeds.2019.11.011 31982088 · DOI
  29. [36]Li W, Peng A, Deng S,. Do premature and postterm birth increase the risk of epilepsy? an updated meta-analysis. Epilepsy Behav. 2019; 97: 83- 91. doi: 10.1016/j.yebeh.2019.05.016 31202097 · DOI
  30. [37]Chen D, Huang M, Yin Y,. Risk factors of cerebral palsy in children: a systematic review and meta-analysis. Transl Pediatr. 2022; 11(4): 556- 564. doi: 10.21037/tp-22-78 35558974 PMC9085939 · DOI
  31. [38]Louise T, Nauf Bendar AS, Durighel G, Frost G, Bell J. The effect of preterm birth on adiposity and metabolic pathways and the implications for later life. Clin Lipidol. 2012; 7(3): 275- 288. doi: 10.2217/clp.12.32 · DOI
  32. [39]Mathai S, Derraik JG, Cutfield WS,. Increased adiposity in adults born preterm and their children. PLoS One. 2013; 8(11): e81840. doi: 10.1371/journal.pone.0081840 24278462 PMC3835734 · DOI
  33. [40]Embleton ND, Korada M, Wood CL, Pearce MS, Swamy R, Cheetham TD. Catch-up growth and metabolic outcomes in adolescents born preterm. Arch Dis Child. 2016; 101(11): 1026- 1031. doi: 10.1136/archdischild-2015-310190 27288431 · DOI
  34. [41]Paquette K, Coltin H, Boivin A, Amre D, Nuyt AM, Luu TM. Cancer risk in children and young adults born preterm: a systematic review and meta-analysis. PLoS One. 2019; 14(1): e0210366. doi: 10.1371/journal.pone.0210366 30608983 PMC6319724 · DOI
  35. [42]Chu A, Heck JE, Ribeiro KB,. Wilms’ tumour: a systematic review of risk factors and meta-analysis. Paediatr Perinat Epidemiol. 2010; 24(5): 449- 469. doi: 10.1111/j.1365-3016.2010.01133.x 20670226 · DOI
  36. [43]Glinianaia SV, Morris JK, Best KE,. Long-term survival of children born with congenital anomalies: a systematic review and meta-analysis of population-based studies. PLoS Med. 2020; 17(9): e1003356. doi: 10.1371/journal.pmed.1003356 32986711 PMC7521740 · DOI
  37. [44]Kase JS, Visintainer P. The relationship between congenital malformations and preterm birth. J Perinat Med. 2007; 35(6): 538- 542. doi: 10.1515/JPM.2007.132 18052839 · DOI
  38. [45]Crump C, Groves A, Sundquist J, Sundquist K. Association of preterm birth with long-term risk of heart failure into adulthood. JAMA Pediatr. 2021; 175(7): 689- 697. doi: 10.1001/jamapediatrics.2021.0131 33818601 PMC8022265 · DOI · Paper page
  39. [46]Crump C, Howell EA, Stroustrup A, McLaughlin MA, Sundquist J, Sundquist K. Association of preterm birth with risk of ischemic heart disease in adulthood. JAMA Pediatr. 2019; 173(8): 736- 743. doi: 10.1001/jamapediatrics.2019.1327 31157896 PMC6547251 · DOI
  40. [47]Crump C, Sundquist J, Sundquist K. Stroke risks in adult survivors of preterm birth: national cohort and cosibling study. Stroke. 2021; 52(8): 2609- 2617. doi: 10.1161/STROKEAHA.120.033797 34134503 PMC8316309 · DOI · Paper page
  41. [48]Crump C, Sundquist J, Sundquist K. Preterm birth and risk of type 1 and type 2 diabetes: a national cohort study. Diabetologia. 2020; 63(3): 508- 518. doi: 10.1007/s00125-019-05044-z 31802143 PMC6997251 · DOI
  42. [50]Been JV, Lugtenberg MJ, Smets E,. Preterm birth and childhood wheezing disorders: a systematic review and meta-analysis. PLoS Med. 2014; 11(1): e1001596. doi: 10.1371/journal.pmed.1001596 24492409 PMC3904844 · DOI
  43. [51]Bertagnolli M, Luu TM, Lewandowski AJ, Leeson P, Nuyt AM. Preterm birth and hypertension: is there a link? Curr Hypertens Rep. 2016; 18(4): 28. doi: 10.1007/s11906-016-0637-6 26951245 · DOI
  44. [52]Carr H, Cnattingius S, Granath F, Ludvigsson JF, Edstedt Bonamy AK. Preterm birth and risk of heart failure up to early adulthood. J Am Coll Cardiol. 2017; 69(21): 2634- 2642. doi: 10.1016/j.jacc.2017.03.572 28545637 · DOI
  45. [53]Chehade H, Simeoni U, Guignard JP, Boubred F. Preterm birth: long term cardiovascular and renal consequences. Curr Pediatr Rev. 2018; 14(4): 219- 226. doi: 10.2174/1573396314666180813121652 30101715 PMC6416185 · DOI
  46. [54]Skudder-Hill L, Ahlsson F, Lundgren M, Cutfield WS, Derraik JGB. Preterm birth is associated with increased blood pressure in young adult women. J Am Heart Assoc. 2019; 8(12): e012274. doi: 10.1161/JAHA.119.012274 31164036 PMC6645636 · DOI
  47. [55]Nosarti C, Reichenberg A, Murray RM,. Preterm birth and psychiatric disorders in young adult life. Arch Gen Psychiatry. 2012; 69(6): E1- E8. doi: 10.1001/archgenpsychiatry.2011.1374 22660967 · DOI
  48. [56]Risnes KR, Vatten LJ, Baker JL,. Birthweight and mortality in adulthood: a systematic review and meta-analysis. Int J Epidemiol. 2011; 40(3): 647- 661. doi: 10.1093/ije/dyq267 21324938 · DOI · Paper page
  49. [57]Wilcox AJ. On the importance—and the unimportance—of birthweight. Int J Epidemiol. 2001; 30(6): 1233- 1241. doi: 10.1093/ije/30.6.1233 11821313 · DOI
  50. [58]D’Onofrio BM, Class QA, Rickert ME, Larsson H, Långström N, Lichtenstein P. Preterm birth and mortality and morbidity: a population-based quasi-experimental study. JAMA Psychiatry. 2013; 70(11): 1231- 1240. doi: 10.1001/jamapsychiatry.2013.2107 24068297 PMC3823714 · DOI
  51. [59]Moster D, Lie RT, Markestad T. Long-term medical and social consequences of preterm birth. N Engl J Med. 2008; 359(3): 262- 273. doi: 10.1056/NEJMoa0706475 18635431 · DOI · Paper page
  52. [60]Binet ME, Bujold E, Lefebvre F, Tremblay Y, Piedboeuf B, Network CN; Canadian Neonatal Network™. Role of gender in morbidity and mortality of extremely premature neonates. Am J Perinatol. 2012; 29(3): 159- 166. doi: 10.1055/s-0031-1284225 21818733 · DOI
  53. [61]Ito M, Tamura M, Namba F; Neonatal Research Network of Japan. Role of sex in morbidity and mortality of very premature neonates. Pediatr Int. 2017; 59(8): 898- 905. doi: 10.1111/ped.13320 28477387 · DOI
  54. [62]Dolan SM, Gross SJ, Merkatz IR,. The contribution of birth defects to preterm birth and low birth weight. Obstet Gynecol. 2007; 110(2 Pt 1): 318- 324. doi: 10.1097/01.AOG.0000275264.78506.63 17666606 · DOI
  55. [63]Sorenson SB. Gender disparities in injury mortality: consistent, persistent, and larger than you’d think. Am J Public Health. 2011; 101(Suppl 1)(suppl 1): S353- S358. doi: 10.2105/AJPH.2010.300029 21778511 PMC3222499 · DOI
  56. [64]Toigo S, Pollock NJ, Liu L, Contreras G, McFaull SR, Thompson W. Fatal and non-fatal firearm-related injuries in Canada, 2016-2020: a population-based study using three administrative databases. Inj Epidemiol. 2023; 10(1): 10. doi: 10.1186/s40621-023-00422-z 36788597 PMC9930327 · DOI
  57. [65]Raju TNK, Buist AS, Blaisdell CJ, Moxey-Mims M, Saigal S. Adults born preterm: a review of general health and system-specific outcomes. Acta Paediatr. 2017; 106(9): 1409- 1437. doi: 10.1111/apa.13880 28419544 · DOI · Paper page
  58. [66]Raju TNK, Pemberton VL, Saigal S, Blaisdell CJ, Moxey-Mims M, Buist S; Adults Born Preterm Conference Speakers and Discussants. Long-Term Healthcare Outcomes of Preterm Birth: An Executive Summary of a Conference Sponsored by the National Institutes of Health. J Pediatr. 2017; 181: 309- 318.e1. doi: 10.1016/j.jpeds.2016.10.015 27806833 · DOI
  59. [67]Doyle CM, Lix LM, Hemmelgarn BR, Paterson JM, Renoux C. Data variability across Canadian administrative health databases: differences in content, coding, and completeness. Pharmacoepidemiol Drug Saf. 2020; 29(suppl 1): 68- 77. doi: 10.1002/pds.4889 31507029 · DOI

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Authors
Ahmed, A. M., Grandi, S. M., Pullenayegum, E., McDonald, S. D., Beltempo, M., Premji, S. S., Pole, J. D., Bacchini, F., Shah, P. S., & Pechlivanoglou, P.
Affiliations
  • Wake Forest University Health Sciences (US)
  • Hospital for Sick Children (CA)
  • McMaster University (CA)
  • McGill University (CA)
  • Queen's University (CA)
  • The University of Queensland (AU)
  • Canadian Premature Babies Foundation (CA)
  • Mount Sinai Hospital (CA)
Corresponding author
Ahmed, Asma M.
ORCID
Venue
JAMA Network Open
Publisher
American Medical Association (AMA)
Published
2024-11-20
Volume
7
Issue
11
Pages
e2445871
ISSN
2574-3805 (ISSN-L)
DOI
10.1001/jamanetworkopen.2024.45871
PMC
PMC11579792
OpenAlex
W4404568140
Cited by
49
References
3
Citations by year
2026: 31 · 2025: 18
FWCI
33.18
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • JAMA Network Open (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • PubMed Central (publishedVersion, cc-by)
Funders
Canadian Institutes of Health Research
Topics
  • Health Sciences › Medicine › Pediatrics, Perinatology and Child Health › Infant Development and Preterm Care
  • Health Sciences › Health Professions › General Health Professions › Maternal and Neonatal Healthcare
  • Health Sciences › Medicine › Epidemiology › Preterm Birth and Chorioamnionitis
Keywords
preterm birth, mortality risk, all-cause mortality, cause-specific mortality, neonatal mortality, gestational age, term birth comparison, long-term outcomes, infant mortality, Canada, risk difference, relative risk, hazard ratio, coarsened exact matching, confounding adjustment
MeSH terms
Adult, Canada, Cause of Death, Child, Child, Preschool, Female, Gestational Age, Humans, Infant, Infant Mortality, Infant, Newborn, Male, Pregnancy, Risk Factors, Cohort Studies, Proportional Hazards Models, Premature Birth, Young Adult

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