@article {Augerjech.2009.102350, author = {Nathalie Auger and Federico Roncarolo and Sam Harper}, title = {Increasing educational inequality in preterm birth in Qu{\'e}bec, Canada, 1981{\textendash}2006}, elocation-id = {jech.2009.102350}, year = {2010}, doi = {10.1136/jech.2009.102350}, publisher = {BMJ Publishing Group Ltd}, abstract = {Background Few studies have evaluated the relationship between preterm birth (PTB) and maternal education over time. We sought to determine whether educational inequalities in PTB have increased in Qu{\'e}bec, Canada.Methods The authors analysed 2 124 909 singleton live births from 1981 to 2006, and computed the Relative Index of Inequality (RII) and Slope Index of Inequality (SII) with 95\% CIs for the relationship between maternal education and extreme, very or moderate PTB (<=27, 28{\textendash}31, and 32{\textendash}36 completed weeks of gestation, respectively) for five periods (1981{\textendash}1985, 1986{\textendash}1990, 1991{\textendash}1995, 1996{\textendash}2000, 2001{\textendash}2006), adjusting for maternal age, marital status, birthplace, language spoken at home, parity and infant sex.Results Average rates of extreme and moderate PTB increased over time but decreased for very PTB. A statistically significant increase in the RII over time was present for extreme and moderate PTB. The adjusted RII for extreme PTB increased from 1.58 (95\% CI 1.24 to 2.01) in 1981{\textendash}1985 to 3.11 (95\% CI 2.54 to 3.81) in 2001{\textendash}2006. For moderate PTB, the corresponding RIIs were 1.53 (95\% CI 1.44 to 1.61) and 1.91 (95\% CI 1.81 to 2.01). Absolute differences in the PTB proportion between the least and most educated mothers increased from 1981 to 2006 for extreme (adjusted SII 0.11\% vs 0.28\%) and moderate PTB (adjusted SII 1.67\% vs 3.11\%). Absolute differences in the proportion very PTB did not increase.Conclusions Relative and absolute educational inequalities in extreme and moderate PTB have increased over time in Qu{\'e}bec. Relative increases were largest for extreme PTB, and absolute increases were largest for moderate PTB.}, issn = {0143-005X}, URL = {https://jech.bmj.com/content/early/2010/07/12/jech.2009.102350}, eprint = {https://jech.bmj.com/content/early/2010/07/12/jech.2009.102350.full.pdf}, journal = {Journal of Epidemiology \& Community Health} }