A Case-Control Investigation of Perinatal Risk Factors for Childhood IDDM in Northern Ireland and Scotland

  1. Susan K Cole, MD
  1. Department of Epidemiology and Public Health, Scottish Health Service Common Services Agency Edinburgh, Scotland
  2. Department of Child Health, Scottish Health Service Common Services Agency Edinburgh, Scotland
  3. The Queen's University of Belfast, Belfast, Northern Ireland; Sir George E. Clark Metabolic Unit, Scottish Health Service Common Services Agency, Royal Victoria Hospital Belfast, Northern Ireland
  4. Department of Public Health Medicine, Scottish Health Service Common Services Agency, Tayside Health Board Dundee, Scotland
  5. Information and Statistics Division, Scottish Health Service Common Services Agency Edinburgh, Scotland
  1. Address correspondence and reprint requests to Christopher C. Patterson, PhD, Department of Epidemiology and Public Health, The Queen's University of Belfast, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BJ, United Kingdom.

Abstract

OBJECTIVE To identify perinatal risk factors for childhood insulin-dependent diabetes mellitus (IDDM) and determine if they differ between early-onset and lateonset disease.

RESEARCH DESIGN AND METHODS We selected 258 diabetic children in Northern Ireland and 271 diabetic children in Scotland from population-based registers. For each diabetic child, five matched control subjects were drawn from the same population. All perinatal data were recorded routinely at birth. Odds ratios (ORs) were estimated for parental age, social class, breast-feeding, deprivation measures, and other perinatal variables.

RESULTS Scottish data indicated an increased risk among children born to older mothers (OR = 2.43, 95% confidence interval [CI] 1.49–3.97 for mothers >35 years of age relative to those <25 years of age). Northern Ireland data showed no such effect. Only Northern Ireland data showed an excess risk in children of professional or managerial families (OR = 1.51, 95% CI 1.11–2.04). A small but nonsignificant reduction in risk among breast-fed children was observed only after adjustment for social class (OR = 0.76, 95% CI 0.54–1.07). Deprivation measures were associated with reductions in risk. Children delivered by cesarean section were at increased risk in both Northern Ireland (OR = 1.66,95% CI 1.10–2.50) and Scottish (OR = 1.70,95% CI 1.12–2.59) data. In Northern Ireland data only, children of first pregnancies were at increased risk (OR = 1.41, 95% CI 1.03–1.93). Both data sets indicated that a first pregnancy was a more important risk factor for early-onset disease than for late-onset disease.

CONCLUSIONS Many reported risk factors are weak and show inconsistencies between studies. They may be secondary to more direct, as-yet-undiscovered risk factors. Although irrelevant in the majority of cases, the increased risk associated with delivery by cesarean section deserves further study.

  • Received April 8, 1993.
  • Accepted November 18, 1933.
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