Aims/hypothesis: Offspring of mothers with diabetes are at increased risk of metabolic disorders in later life. Increased offspring BMI is a plausible mediator. We performed a systematic review and meta-analysis of studies examining offspring BMI z score in childhood in relation to maternal diabetes.
Methods: Papers reporting BMI z scores for offspring of diabetic (all types, and pre- and during-pregnancy onset) and non-diabetic mothers were included. Citations were identified in PubMed; bibliographies of relevant articles were hand-searched and authors contacted for additional data where necessary. We compared offspring BMI z score with and without adjustment for maternal pre-pregnancy BMI. We performed fixed effect meta-analysis except where significant heterogeneity called for use of a random effects analysis.
Results: Data were available from nine studies. In the diabetic group unadjusted mean offspring BMI z score was 0.28 higher (all diabetic mothers vs controls (95% CI 0.09, 0.47; p = 0.004; nine studies; offspring of diabetic mothers n = 927, controls n = 26,384) and with adjustment for maternal pre-pregnancy BMI, 0.07 higher (95% CI -0.15, 0.28; p = 0.54; three studies; offspring of diabetic mothers n = 244, controls n = 11,206). There was no evidence of a difference in offspring BMI z score in relation to type of diabetes (gestational vs type 1, p = 0.95).
Conclusions/interpretation: Maternal diabetes is associated with increased offspring BMI z score, although this is no longer apparent after adjustment for maternal pre-pregnancy BMI in the limited number of studies in which this is reported. Causal mediators of the effect of maternal diabetes on offspring outcomes remain to be established; we recommend that future research includes adjustment for maternal pre-pregnancy BMI.