Abstract
OBJECTIVES: Breastfeeding is associated with improved health. Surveillance data show that breastfeeding initiation rates have increased; however, limited work has examined trends in socio-economic inequalities in initiation. The study’s research question was whether socio-economic inequalities in breastfeeding initiation have changed over the past 20 years.
METHODS: This population-based study is a project within PATHS Equity for Children. Analyses used hospital discharge data for Manitoba mother–infant dyads with live births, 1988-2011 (n=316,027). Income quintiles were created, each with ≈20% of dyads. Three-year, overall and by-quintile breastfeeding initiation rates were estimated for Manitoba and two hospitals. Age-adjusted rates were estimated for Manitoba. Rates were modelled using generalized linear models. Three measures, rate ratios (RRs), rate differences (RDs) and concentration indices, assessed inequality at each time point. We also compared concentration indices with Gini coefficients to assess breastfeeding inequality vis-à-vis income inequality. Trend analyses tested for changes over time.
RESULTS: Manitoba and Hospital A initiation rates increased; Hospital B rates did not change. Significant inequalities existed in nearly every period, across all three measures: RRs, RDs and concentration indices. RRs and concentration indices suggested little to no change in inequality from 1988 to 2011. RDs for Manitoba (comparing initiation in the highest to lowest income quintiles) did not change significantly over time. RDs decreased for Hospital A, suggesting decreasing socio-economic inequalities in breastfeeding; RDs increased for Hospital B. Income inequality increased significantly in Manitoba during the study period.
CONCLUSIONS: Overall breastfeeding initiation rates can improve while inequality persists or worsens.
Keywords: Health status disparities, social determinants of health, social class, breast feeding
Résumé
OBJECTIFS : L’allaitement est associé à une meilleure santé. Selon les données de surveillance, les taux d’initiation de l’allaitement maternel augmentent, mais peu d’études examinent les tendances des inégalités socioéconomiques dans l’initiation de l’allaitement. Notre question de recherche était de savoir si les inégalités socioéconomiques dans l’initiation de l’allaitement maternel ont changé au cours des 20 dernières années.
MÉTHODE : Cette étude populationnelle s’inscrit dans le programme PATHS Equity for Children. Nos analyses ont utilisé les données de sortie d’hôpital du Manitoba pour les dyades mère-nourrisson avec naissances vivantes de 1988 à 2011 (n=316 027). Des quintiles de revenu ont été créés, contenant chacun ≈20 % des dyades. Les taux d’initiation de l’allaitement maternel sur trois ans, globaux et par quintile, ont été estimés pour l’ensemble du Manitoba et pour deux hôpitaux. Des taux ajustés selon l’âge ont été estimés pour le Manitoba. Les taux ont été modélisés à l’aide de modèles linéaires généralisés. Trois indicateurs, les ratios des taux (RT), les différences de taux (DT) et les indices de concentration, ont permis d’évaluer l’inégalité à chaque point dans le temps. Nous avons aussi comparé les indices de concentration aux coefficients de Gini pour évaluer l’inégalité dans l’allaitement par rapport à l’inégalité des revenus. Des analyses des tendances ont servi à déceler les changements au fil du temps.
RÉSULTATS : Les taux d’initiation du Manitoba et de l’hôpital A ont augmenté; les taux de l’hôpital B n’ont pas changé. Des inégalités significatives étaient présentes dans pratiquement toutes les périodes et pour les trois indicateurs: RT, DT et indices de concentration. Les RT et les indices de concentration ont fait état de changements faibles ou nuls dans l’inégalité de 1988 à 2011. Les DT pour le Manitoba (comparant l’initiation du quintile de revenu supérieur au quintile inférieur) n’ont pas significativement changé au fil du temps. Les DT ont diminué pour l’hôpital A, ce qui pourrait signaler une baisse des inégalités socioéconomiques dans l’allaitement; les DT ont augmenté pour l’hôpital B. L’inégalité des revenus a significativement augmenté au Manitoba sur la période de l’étude.
CONCLUSIONS : Les taux d’initiation de l’allaitement maternel peuvent s’améliorer globalement alors que l’inégalité subsiste ou s’aggrave.
Motsclés: disparités d’état sanitaire, déterminants sociaux de la santé, classe sociale, allaitement maternel
Footnotes
Acknowledgements: This work was supported by the Canadian Institutes of Health Research (CIHR) and the Heart & Stroke Foundation of Canada under the program of research entitled PATHS Equity for Children: A Program of Research Into What Works to Reduce the Gap for Manitoba’s Children. The authors acknowledge the Manitoba Centre for Health Policy (MCHP) for use of data contained in the Population Health Research Data Repository under project # 2012-006 (HIPC #2011/2012 — 24C) and provided by Manitoba Health and Statistics Canada. The results and conclusions are those of the authors, and no official endorsement by MCHP, Manitoba Health or other data providers is intended or should be inferred. Patricia Martens wishes to acknowledge funding from the CIHR and the Public Health Agency of Canada (PHAC) for her CIHR/PHAC Applied Public Health Research Chair (2008-2014). Marni Brownell acknowledges the financial support of the Government of Manitoba through the Manitoba Centre for Health Policy Population-Based Child Health Research Award. Alan Katz acknowledges the support of the Manitoba Health Research Council and the Heart & Stroke Foundation for his Research Chair in Primary Prevention (2013–2018). The authors thank Joshua Ginter for his helpful edits on this article and the reviewers for their thoughtful feedback. The authors also thank project advisory group members Dr. Michael Kramer, Ms. Dawn Ridd and Ms. Linda Romphf.
The PATHS Equity Team: James Bolton, Marni Brownell, Charles Burchill, Elaine Burland, Mariette Chartier, Dan Chateau, Malcolm Doupe, Greg Finlayson, Randall Fransoo, Chun Yan Goh, Mingming Hu, Doug Jutte, Alan Katz, Laurence Katz, Lisa Lix, Patricia J. Martens, Colleen Metge, Nathan C. Nickel, Colette Raymond, Les Roos, Noralou Roos, Rob Santos, Joykrishna Sarkar, Mark Smith, Carole Taylor and Randy Walld.
Conflict of Interest: None to declare.
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