Exposure to dental amalgam restorations in pregnant women

The Norwegian Mother and Child Cohort Study (MoBa) started in 1999 to identify environmental factors that could be involved in mechanisms leading to disease. Questions have been raised about potential risks to the fetus from prenatal exposure to mercury from amalgam fillings in pregnant women. The aim of the present study was to identify factors potentially associated with amalgam fillings in pregnant women participating in the Norwegian Mother and Child Cohort Study (MoBa). An additional aim was to obtain information about dental treatment in the cohort.

Total of 67,355 pregnancies from the MoBa study were included in the present study. Information regarding age, education, smoking habits, alcohol consumption, weight, and height for the women was obtained from a questionnaire that was filled in at the 17th week of pregnancy. In another questionnaire, which was sent to all participants in the 30th week of pregnancy, the women reported types of dental treatment during pregnancy, total number of teeth, and number of teeth with amalgam fillings. The self-assessed number of teeth and number of teeth with amalgam fillings were validated in an external sample of 97 women of childbearing age.

Odds ratio for having more than 12 teeth with amalgam fillings increased considerably with age. Other significant risk factors for having high exposure to amalgam were low education, high body mass index (BMI), and smoking during pregnancy. Women with the lowest levels of education had a twofold increased odds ratio of having more than 12 teeth filled with amalgam compared with women who had more than 4 years of university studies. According to the results from the validation of self-assessed number of teeth with amalgam fillings, the information obtained was reliable.

Age, education, smoking habits, and BMI were associated with amalgam exposure.