Dental amalgams and risk of gestational hypertension in the MIREC study

The potential association between the presence or replacement of dental amalgams and gestational hypertension (GH) is unclear.

To assess the association between the presence or replacement of dental amalgams and the risk of GH in a prospective cohort study.

We assessed dental amalgam status (presence or replacement), blood mercury concentrations, and measured blood pressure (BP) in 1817 pregnant women recruited in 10 Canadian cities. BP was assessed in each trimester of pregnancy and mercury concentrations in 1st and 3rd trimesters. Logistic regression analysis was performed to estimate the adjusted odds ratios (aOR) and 95% confidence intervals (CI) for the associations between dental amalgam status and GH. Concurrent measures with systolic BP (SBP) and diastolic BP (DBP) were assessing through linear generalized estimating equations.

Dental amalgam status was weakly statistically correlated with mercury concentrations but there was no evidence of an association with GH in women having 1-4 (aOR = 1.31 (0.92, 1.85)) or ≥ 5 dental amalgams (aOR = 1.32 (0.86, 2.04)), compared to women without amalgam reported at first trimester. Dental amalgam replacement reported in the first or third trimester was similarly not associated with GH (aOR = 0.75 (0.40, 1.42) and 0.73 (0.39, 1.34), respectively) but with SBP (beta = -1.58 (-2.95, -0.02)).

We found weak correlations between dental amalgams and blood mercury among pregnant women. However, the presence of dental amalgams or their replacement was not associated with GH but with decreased SBP for the replacement. Further studies are required.