Association between prenatal metals exposure and blood pressure in 5-6 years children: A birth cohort study.

Background: The trajectory of blood pressure (BP) from childhood to early middle age suggested that individuals with elevated BP in early childhood were more likely to be affected by cardiovascular disease in adulthood. Exposure to metals may affect BP in children, and pregnancy is a sensitive time for metal exposure. This study assessed the relationship between different stages of prenatal exposure to metals or metal mixtures and BP in children aged 5-6 years.

Methods: The study included 2535, 2680, 2534 mother-child pairs in three trimesters, from the Ma'anshan birth cohort study (MABC). We collected maternal blood samples during pregnancy and measured the serum levels of four metals (arsenic, selenium, cadmium, and mercury). BP was measured in children aged 5-6 years. A linear regression model and Bayesian kernel machine regression (BKMR) were used to explore associations between prenatal exposure to metals at different stages and multiple metal exposure with BP in children aged 5-6 years.

Results: Associations were observed between the arsenic in the third trimester and children's diastolic blood pressure (DBP) (β = 0.88, 95% CI: 0.44, 1.33), systolic blood pressure (SBP) (β = 0.72, 95% CI: 0.19, 1.24) and mean arterial pressure (MAP) (β = 0.83, 95% CI: 0.42, 1.23), as well as between the mercury and children's DBP (β = 0.65, 95% CI: 0.13, 1.16) and MAP (β = 0.60, 95% CI: 0.14, 1.07). The BKMR analysis showed that multiple metals had a significant positive joint effect on children's DBP, SBP and MAP. A potential interaction between arsenic and mercury was observed (β = -0.85, 95% CI: -1.62, -0.08).

Conclusions: Exposure to arsenic and mercury during pregnancy was associated with altered BP in children. The third trimester may represent an important window of opportunity to reduce the effects of metal exposure on children's blood pressure and long-term health.