Have we left some behind? Trends in socio-economic inequalities in breastfeeding initiation: a population-based epidemiological surveillance study.

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.