Association between placental global DNA methylation and blood pressure during human pregnancy.

Objective: Gene-specific placental DNA methylation patterns differ between normal pregnancies and pregnancies complicated by hypertension. However, whether global placental DNA methylation is associated with maternal blood pressure remains controversial.

Methods: Using multiple linear regression models, we analysed the association between maternal mean arterial pressure (MAP) at the third trimester of pregnancy and global DNA methylation in the placenta in 922 mothers using LC-ESI-MS/MS. To better characterize the contribution of genetic or epigenetic mechanisms, we performed isolated analyses in mothers with and without a family history of hypertension.

Results: Mean placental global DNA methylation was 3.00 ± 0.46%. A significant negative correlation between placental global DNA methylation and mean arterial blood pressure (MAP) in the third trimester could be observed (P = 0.023, r = -0.075). This association remained significant after adjusting for confounders. In placenta samples from mothers with a family history of hypertension, mean maternal MAP was higher (86.1 ± 8.1 vs. 84.6 ± 7.5, P < 0.01) and placental global DNA methylation was lower (2.94 ± 0.43 vs. 3.04 ± 0.47, P < 0.01) compared with samples without a family history of hypertension. Furthermore, the significant independent negative correlation between global placental DNA methylation and MAP was only found in mothers without a family history of hypertension.

Conclusion: This study showed an independent negative correlation between placental global DNA methylation and maternal MAP in mothers without a family history of hypertension.