title: Multiple maternities and neighborhood income.
abstract: This study aimed to examine differences in multiple maternities by neighborhood-income levels in Toronto, Canada. Hospital records were used to perform secondary analysis of 144,731 maternities resulting in single or multiple infants live-born to mothers residing in the City of Toronto 1996 to 2001. The independent variable was neighborhood income, defined as mean household neighborhoodincome quintiles. Multiple logistic regression analysis was used to compute adjusted odds ratios (AORs) and 95% confidence intervals (CIs). Differences by income levels were found in twin maternities but not in higher order maternities. Twin maternities were more likely to occur in the richest neighborhood-income quintile compared to the rest of the population (AOR: 1.25, 95% CI: 1.10-1.41), after adjustment for potential confounders. The positive association between high neighborhood income and twin maternities found in this study suggests that the richest neighborhoods select families whose characteristics pose them at increased risk of having twins. Further studies are needed to clarify the underlying mechanisms leading to socioeconomic differences in multiple births.
authors.affiliation: Centre for Research in Inner City Health, St Michael's Hospital, Toronto, Canada. marcelo.urquia@utoronto.ca
authors.forename: Marcelo Luis
authors.initials: ML
authors.lastname: Urquia
authors.forename: John William
authors.initials: JW
authors.lastname: Frank
authors.forename: Richard Henry
authors.initials: RH
authors.lastname: Glazier
authors.forename: Rahim
authors.initials: R
authors.lastname: Moineddin
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007182:Income; D007231:Infant, Newborn; D008297:Male; D009864:Ontario; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D027724:Reproductive Techniques, Assisted / Q000191:economics / Q000706:statistics & numerical data; D012111:Residence Characteristics; D012189:Retrospective Studies; D012959:Socioeconomic Factors