In-utero exposure to maternal diabetes and the risk of cerebral palsy: a population-based cohort study

Background — Evidence on the effects of in utero exposure to maternal diabetes on cerebral palsy in offspring is limited. We aimed to examine the effects of pre-gestational (PGDM) and gestational diabetes (GDM) separately on CP risk and the mediating role of increased fetal size.

Methods — In a population-based study, we included all live births in Ontario, Canada, between 2002–2017 followed up through 2018 (n=2,110,177). Using administrative health data, we estimated crude and adjusted associations between PGDM or GDM and CP using Cox proportional hazards models to account for unequal follow-up in children. For the mediation analysis, we used marginal structural models to estimate the controlled direct effect of PGDM (and GDM) on the risk of CP not mediated by large-for-gestational age (LGA).

Results — During the study period, 5,317 children were diagnosed with CP (187 exposed to PGDM and 171 exposed to GDM). Children of mothers with PGDM showed an increased risk {hazard ratio [HR]: 1.84 [95% confidence interval (CI): 1.59, 2.14]} after adjusting for maternal sociodemographic and clinical factors. We found no associations between GDM and CP (adjusted HR: 0.91 (0.77, 1.06)). Our mediation analysis estimated that LGA explained 14% of the PDGM–CP association.

Conclusions —In this population-based birth cohort study, maternal pre-gestational diabetes was associated with increased risk of CP, and the increased risk was not substantially mediated by the increased fetal size.