Abstract
OBJECTIVE: To evaluate a possible association between neighbourhood socio-economic status and spontaneous premature birth in Alberta births.
METHODS: The study design was a retrospective cohort of all births in Alberta for the years 2001 and 2006. The primary outcome was spontaneous preterm birth at <37 weeks gestation. Neighbourhood socio-economic status was measured by the Pampalon Material Deprivation Index for each Statistics Canada census dissemination area. Births were linked to dissemination area using maternal postal codes.
RESULTS: The analysis comprised 73,585 births, in which the rate of spontaneous preterm delivery at <37 weeks was 5.3%. The rates of spontaneous preterm delivery for each neighbourhood socio-economic category ranged from 4.9% (95% CI 4.5%–5.2%) in the highest category to 6.3% (95% CI 6.0%–6.7%) in the lowest (p<0.001). After controlling for smoking, parity, maternal age and year, we found that women living in the highest socio-economic status neighbourhoods had an adjusted spontaneous preterm birth rate of 5.1% (95% CI 4.7%–5.5%) compared to 6.0% (95% CI 5.6%–6.4%) for women living in the lowest (p=0.003).
CONCLUSION: This study documented a modest increase in the risk of spontaneous preterm birth with low socio-economic status. The possibility of confounding bias cannot be ruled out.
Keywords: Social class, obstetric labour, premature
Résumé
OBJECTIF : Évaluer une association possible entre le statut socioéconomique du quartier et les accouchements prématurés spontanés parmi les naissances en Alberta.
MÉTHODE : Le protocole d’étude comportait une cohorte rétrospective de toutes les naissances survenues en Alberta en 2001 et en 2006. Le principal résultat était la prématurité spontanée à <37 semaines de gestation. Le statut socioéconomique du quartier a été mesuré selon l’indice de défavorisation matérielle de Pampalon pour chaque aire de diffusion du recensement de Statistique Canada. Les naissances ont été liées aux aires de diffusion à l’aide des codes postaux maternels.
RÉSULTATS : L’analyse a compris 73 585 naissances, parmi lesquelles le taux d’accouchements prématurés spontanés à <37 semaines était de 5,3%. Les taux d’accouchements prématurés spontanés pour chaque catégorie de statut socioéconomique du quartier variaient de 4,9% (IC de 95%: 4,5 %–5,2 %) dans la catégorie la plus élevée à 6,3% (IC de 95%: 6,0%–6,7 %) dans la catégorie la moins élevée (p<0,001). Compte tenu du tabagisme, de la parité, de l’âge maternel et de l’année, nous avons constaté que les femmes vivant dans les quartiers au statut socioéconomique le plus élevé avaient un taux ajusté de prématurité spontanée de 5,1% (IC de 95%: 4,7%–5,5 %), contre 6,0% (IC de 95%: 5,6%–6,4%) pour les femmes vivant dans les quartiers au statut économique le plus faible (p=0,003).
CONCLUSION : Cette étude fait état d’une légère augmentation du risque de prématurité spontanée liée au faible statut socioéconomique. La possibilité d’un biais dû aux facteurs de confusion ne peut être écartée.
Motsclés: classe sociale, travail obstétrical, prématuré
Footnotes
Acknowledgements: The author’s research group (Partnership for Research and Education in Mothers and Infants) is supported by an unrestricted grant from Abbott Nutrition.
Conflict of Interest: None to declare.
References
- 1.Proc Natl Acad Sci U S A. 2012.
- 2.Black RE, Cousens S, Johnson HL, Lawn JE, Rudan I, Bassani DG, et al. Global, regional, and national causes of child mortality in 2008: A systematic analysis. Lancet. 2010;375(9730):1969–87. doi: 10.1016/S0140-6736(10)60549-1. [DOI] [PubMed] [Google Scholar]
- 3.Slattery MM, Morrison JJ. Preterm delivery. Lancet. 2002;360:1489–97. doi: 10.1016/S0140-6736(02)11476-0. [DOI] [PubMed] [Google Scholar]
- 4.Langhoff-Roos J, Kesmodel U, Jacobsson B, Rasmussen S, Vogel I. Spontaneous preterm delivery in primiparous women at low risk in Denmark: Population based study. BMJ. 2006;332(7547):937–39. doi: 10.1136/bmj.38751.524132.2F. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Berkowitz GS, Blackmore-Prince C, Lapinski RH, Savitz D. Risk factors for preterm birth subtypes. Epidemiology. 1998;9:279–85. doi: 10.1097/00001648-199805000-00011. [DOI] [PubMed] [Google Scholar]
- 6.Hendler I, Goldenberg RL, Mercer BM, Iams JD, Meis PJ, Moawad AH, et al. The Preterm Prediction Study: Association between maternal body mass index and spontaneous and indicated preterm birth. Am J Obstet Gynecol. 2005;192(3):882–86. doi: 10.1016/j.ajog.2004.09.021. [DOI] [PubMed] [Google Scholar]
- 7.Ahern J, Pickett KE, Selvin S, Abrams B. Preterm birth among African American and white women: A multilevel analysis of socioeconomic characteristics and cigarette smoking. J Epidemiol Community Health. 2003;57(8):606–11. doi: 10.1136/jech.57.8.606. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Messer LC, Vinikoor LC, Laraia BA, Kaufman JS, Eyster J, Holzman C, et al. Socioeconomic domains and associations with preterm birth. Soc Sci Med. 2008;67(8):1247–57. doi: 10.1016/j.socscimed.2008.06.009. [DOI] [PubMed] [Google Scholar]
- 9.O’Campo P, Xue X, Wang MC, Caughy M. Neighborhood risk factors for low birthweight in Baltimore: A multilevel analysis. Am J Public Health. 1997;87(7):1113–18. doi: 10.2105/AJPH.87.7.1113. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.O’Campo P, Burke JG, Culhane J, Elo IT, Eyster J, Holzman C, et al. Neighborhood deprivation and preterm birth among non-Hispanic Black and White women in eight geographic areas in the United States. Am J Epidemiology. 2008;167(2):155–63. doi: 10.1093/aje/kwm277. [DOI] [PubMed] [Google Scholar]
- 11.Peacock JL, Bland JM, Anderson HR. Preterm delivery: Effects of socioeconomic factors, psychological stress, smoking, alcohol, and caffeine. BMJ. 1995;311(7004):531–35. doi: 10.1136/bmj.311.7004.531. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Ancel PY, Saurel-Cubizolles MJ, Di Renzo GC, Papiernik E, Breart G. Social differences of very preterm birth in Europe: Interaction with obstetric history. Europop Group. Am J Epidemiol. 1999;149(10):908–15. doi: 10.1093/oxfordjournals.aje.a009734. [DOI] [PubMed] [Google Scholar]
- 13.Fairley L, Leyland AH. Social class inequalities in perinatal outcomes: Scotland 1980–2000. J Epidemiol Community Health. 2006;60(1):31–36. doi: 10.1136/jech.2005.038380. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Janghorbani M, Stenhouse E, Millward A, Jones RB. Neighborhood deprivation and preterm birth in Plymouth, UK. J Matern Fetal Neonatal Med. 2006;19(2):85–91. doi: 10.1080/14767050500363428. [DOI] [PubMed] [Google Scholar]
- 15.Bonet M, Smith LK, Pilkington H, Draper ES, Zeitlin J. BMC Pregnancy Childbirth. 2013. Neighbourhood deprivation and very preterm birth in an English and French cohort. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Tuntiseranee P, Olsen J, Chongsuvivatwong V, Limbutara S. Socioeconomic and work related determinants of pregnancy outcome in southern Thailand. J Epidemiol Community Health. 1999;53(10):624–29. doi: 10.1136/jech.53.10.624. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Craig ED, Thompson JM, Mitchell EA. Socioeconomic status and preterm birth: New Zealand trends, 1980 to 1999. Arch Dis Child Fetal Neonatal Ed. 2002;86(3):F142–F146. doi: 10.1136/fn.86.3.F142. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Pampalon R, Hamel D, Gamache P, Raymond G. A deprivation index for health planning in Canada. Chronic Dis Can. 2009;29(4):178–91. [PubMed] [Google Scholar]
- 19.Stata statistical software. College Station TX: StataCorp, 2011.
- 20.Smith GC, Shah I, White IR, Pell JP, Crossley JA, Dobbie R. Maternal and biochemical predictors of spontaneous preterm birth among nulliparous women: A systematic analysis in relation to the degree of prematurity. Int J Epidemiol. 2006;35(5):1169–77. doi: 10.1093/ije/dyl154. [DOI] [PubMed] [Google Scholar]
- 21.Cnattingius S, Mills JL, Yuen J, Eriksson O, Salonen H. The paradoxical effect of smoking in preeclamptic pregnancies: Smoking reduces the incidence but increases the rates of perinatal mortality, abruptio placentae, and intrauterine growth restriction. Am J Obstet Gynecol. 1997;177(1):156–61. doi: 10.1016/S0002-9378(97)70455-1. [DOI] [PubMed] [Google Scholar]
- 22.Burguet A, Kaminski M, Abraham-Lerat L, Schaal JP, Cambonie G, Fresson J, et al. The complex relationship between smoking in pregnancy and very preterm delivery. Results of the Epipage study. BJOG: an International Journal of Obstetrics & Gynaecology. 2004;111(3):258–65. doi: 10.1046/j.1471-0528.2003.00037.x. [DOI] [PubMed] [Google Scholar]
- 23.Marmot M. Social determinants of health inequalities. Lancet. 2005;365(9464):1099–104. doi: 10.1016/S0140-6736(05)74234-3. [DOI] [PubMed] [Google Scholar]
- 24.Veugelers PJ, Yip AM. Socioeconomic disparities in health care use: Does universal coverage reduce inequalities in health? J Epidemiol Community Health. 2003;57(6):424–28. doi: 10.1136/jech.57.6.424. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Joseph KS, Liston RM, Dodds L, Dahlgren L, Allen AC. Socioeconomic status and perinatal outcomes in a setting with universal access to essential health care services. CMAJ. 2007;177(6):583–90. doi: 10.1503/cmaj.061198. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Luo ZC, Wilkins R, Kramer MS. Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System. Effect of neighbourhood income and maternal education on birth outcomes: A population-based study. CMAJ. 2006;174(10):1415–20. doi: 10.1503/cmaj.051096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Kramer MS, Goulet L, Lydon J, Seguin L, McNamara H, Dassa C, et al. Socio-economic disparities in preterm birth: Causal pathways and mechanisms. Paediat Perinat Epidemiol. 2001;15(Suppl2):104–23. doi: 10.1046/j.1365-3016.2001.00012.x. [DOI] [PubMed] [Google Scholar]
- 28.Hodnett ED, Fredericks S. Cochrane Database of Systematic Reviews. 2003. Support during pregnancy for women at increased risk of low birthweight babies. [DOI] [PubMed] [Google Scholar]
- 29.Kramer MS, Lydon J, Seguin L, Goulet L, Kahn SR, McNamara H, et al. Stress pathways to spontaneous preterm birth: The role of stressors, psychological distress, and stress hormones. Am J Epidemiol. 2009;169(11):1319–26. doi: 10.1093/aje/kwp061. [DOI] [PubMed] [Google Scholar]
- 30.Carey JC, Klebanoff MA, Hauth JC, Hillier SL, Thom EA, Ernest JM, et al. Metronidazole to prevent preterm delivery in pregnant women with asymptomatic bacterial vaginosis. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. NEJM. 2000;342(8):534–40. doi: 10.1056/NEJM200002243420802. [DOI] [PubMed] [Google Scholar]
- 31.Klebanoff MA, Carey JC, Hauth JC, Hillier SL, Nugent RP, Thom EA, et al. Failure of metronidazole to prevent preterm delivery among pregnant women with asymptomatic Trichomonas vaginalis infection. NEJM. 2001;345(7):487–93. doi: 10.1056/NEJMoa003329. [DOI] [PubMed] [Google Scholar]
- 32.Ruiz-Mirazo E, Lopez-Yarto M, McDonald SD. Group prenatal care versus individual prenatal care: A systematic review and meta-analyses. JSOGC. 2014;34(3):223–29. doi: 10.1016/S1701-2163(16)35182-9. [DOI] [PubMed] [Google Scholar]