Cardwell, C. R., Stene, L. C., Joner, G., Bulsara, M. K., Cinek, O., Rosenbauer, J., et al. (2010). Maternal age at birth and childhood type 1 diabetes: A pooled analysis of 30 observational studies. Diabetes, 59(2), 486-494. doi: 10.2337/db09-1166
Objective: To investigate whether children born to older mothers have an increased risk of type 1 diabetes by performing a meta-analysis using individual patient data to adjust for recognised confounders.
Research design and methods: Relevant studies published before June 2009 were identified from MEDLINE, Web of Science and EMBASE. Authors of studies were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of maternal age were calculated for each included study, before and after adjustment for potential confounders. Meta-analysis techniques were used to derive combined odds ratios, and investigate heterogeneity between studies.
Results: Data were available for 5 cohort and 25 case-control studies, including 14,724 cases of type 1 diabetes. Overall, there was, on average, a 5% (95% CI 2%, 9%) increase in childhood type 1 diabetes odds per 5 year increase in maternal age (P=0.006), but there was heterogeneity between studies (heterogeneity I2= 70%). In studies with a low risk of bias there was a more marked increase in diabetes odds of 10% per 5 year increase in maternal age. Adjustments for potential confounders little altered these estimates.
Conclusions: There was evidence of a weak but significant linear increase in the risk of childhood type 1 diabetes across the range of maternal ages, but the magnitude of association varied between studies. A very small percentage of the increase in the incidence of childhood type 1 diabetes in recent years could be explained by increases in maternal age.
peer-reviewed, diabetes mellitus, type 1, epidemiology, maternal age