RESUMEN
CONTEXT: Maternal dysglycaemia and prepregnancy obesity are associated with adverse offspring outcomes. Epigenetic mechanisms such as DNA methylation (DNAm) could contribute. OBJECTIVE: To examine relationships between maternal glycaemia, insulinemic status, and dietary glycemic indices during pregnancy and an antenatal behavioral-lifestyle intervention with newborn DNAm. METHODS: We investigated 172 women from a randomized controlled trial of a lifestyle intervention in pregnant women who were overweight or obese. Fasting glucose and insulin concentrations and derived indices of insulin resistance (HOMA-IR), ß-cell function (HOMA-%B), and insulin sensitivity were determined at baseline (15) and 28 weeks' gestation. Dietary glycemic load (GL) and index (GI) were calculated from 3-day food diaries. Newborn cord blood DNAm levels of 850K CpG sites were measured using the Illumina Infinium HumanMethylationEPIC array. Associations of each biomarker, dietary index and intervention with DNAm were examined. RESULTS: Early pregnancy HOMA-IR and HOMA-%B were associated with lower DNAm at CpG sites cg03158092 and cg05985988, respectively. Early pregnancy insulin sensitivity was associated with higher DNAm at cg04976151. Higher late pregnancy insulin concentrations and GL scores were positively associated with DNAm at CpGs cg12082129 and cg11955198 and changes in maternal GI with lower DNAm at CpG cg03403995 (Bonferroni corrected P < 5.99 × 10-8). These later associations were located at genes previously implicated in growth or regulation of insulin processes. No effects of the intervention on cord blood DNAm were observed. None of our findings were replicated in previous studies. CONCLUSION: Among women who were overweight or obese, maternal pregnancy dietary glycemic indices, glucose, and insulin homeostasis were associated with modest changes in their newborn methylome. TRIAL REGISTRATION: ISRCTN29316280.