Abstract
Background
Maternal socioeconomic disadvantage has been associated with increased risk of small-for-gestational-age birth and preterm birth. Few studies, however, have considered maternal education and income simultaneously to better understand the mechanisms underlying perinatal health disparities. This analysis examines both maternal education and income and their association with the risk of small-for-gestational-age birth and preterm birth.
Methods
The study is based on 127,694 singleton live births from the 2006 Canadian Birth-Census Cohort, a national cohort of births registered from May 2004 to May 2006 that were linked to the 2006 long-form Census. Unadjusted rates of small-for-gestational-age birth (sex-specific birth weight below the 10th percentile for gestational age) and preterm birth (before 37 completed weeks of gestation) were estimated across selected maternal characteristics. Logistic regression was used to estimate crude and covariate-adjusted risk ratios of both outcomes according to maternal education and income adequacy quintiles.
Results
Small-for-gestational-age birth was associated with both maternal education and income adequacy, while preterm birth was associated with maternal education only. These findings persisted after taking factors including maternal age, ethnicity, and marital status into account. The results suggest that the mechanism by which maternal education is associated with these outcomes is likely not through income, nor does income replace education as a potentially meaningful measure of socioeconomic position.
Interpretation
The mechanisms underlying associations between socioeconomic position and perinatal health disparities are complex. The results of this study indicate that more than one socioeconomic factor may play a role.
Keywords
Birth weight, educational status, income, perinatal, pregnancy, premature infant
Findings
Socioeconomic disparities in birth outcomes have long been recognized in developed countries. Maternal socioeconomic disadvantage has been associated with increased risk of small-for-gestational-age birth and preterm birth. Small-for-gestational-age infants are at greater risk of neonatal mortality and morbidity, while preterm birth is a leading cause of infant death. [Full Text]
Authors
Tracey Bushnik (tracey.bushnik@canada.ca) is with the Health Analysis Division at Statistics Canada, Ottawa, Ontario. Seungmi Yang and Jay S. Kaufman are with the Department of Epidemiology, Biostatistics and Occupational Health at McGill University. Michael S. Kramer is with the Departments of Pediatrics and of Epidemiology, Biostatistics and Occupational Health at McGill University and the McGill University Health Centre Research Institute. Russell Wilkins is with the Department of Epidemiology and Community Medicine at the University of Ottawa.
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What is already known on this subject?
- Socioeconomic disparities in small-for-gestational-age birth and preterm birth have long been recognized in developed countries.
- Although socioeconomic position is multifaceted, most studies have focused on only one measure, often maternal education or income.
- Few studies have examined maternal education and income together, and even fewer have done so in the context of a publicly funded, universal health care system.
What does this study add?
- A representative national dataset containing information on perinatal outcomes and on maternal education and income is available in Canada.
- When factors including maternal age, ethnicity and marital status were taken into account, small-for-gestational-age birth was associated with both maternal education and income adequacy, whereas preterm birth was associated only with maternal education.
- The mechanism by which maternal education is associated with small-for-gestational-age birth and preterm birth is likely not through income, nor does income replace education as an indicator of socioeconomic position.
- Associations between socioeconomic position and perinatal health disparities are complex, and more than one socioeconomic factor plays a role.
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