Socioeconomic status and perinatal outcomes in a setting with universal access to essential health care services.

BACKGROUND: The health care system in Canada provides essential health services to all women irrespective of socioeconomic status. Our objective was to determine whether perinatal and infant outcomes varied by family income and other socioeconomic factors in this setting.
METHODS: We included all 92,914 women who delivered in Nova Scotia between 1988 and 1995 following a singleton pregnancy. Family income was obtained for 76,440 of these women through a confidential link to income tax records and was divided into 5 groups. Outcomes studied included pregnancy complications, preterm birth, small-for-gestational-age live birth, perinatal death, serious neonatal morbidity, postneonatal death and infant death. Logistic regression models were used to adjust for potential confounders.
RESULTS: Compared with women in the highest family income group, those in the lowest income group had significantly higher rates of gestational diabetes (crude rate ratio [RR] 1.44, 95% confidence interval [CI] 1.21-1.73), preterm birth (crude RR 1.20, 95% CI 1.06-1.35), small-for-gestational-age live birth (crude RR 1.81, 95% CI 1.66-1.97) and postneonatal death (crude RR 5.54, 95% CI 2.21-13.9). The opposite was true for rates of perinatal death (crude RR 0.74, 95% CI 0.56-0.96), and there was no significant difference between the 2 groups in the composite of perinatal death or serious neonatal morbidity (crude RR 1.01, 95% CI 0.82-1.24). Adjustment for behavioural and lifestyle factors accentuated or attenuated socioeconomic differences.
INTERPRETATION: Lower family income is associated with increased rates of gestational diabetes, small-for-gestational-age live birth and postneonatal death despite health care services being widely available at no out-of-pocket expense.