The safety of amalgam as a dental restorative material has been questioned ever since it was introduced 150 years ago (1–3). However, it is unclear whether mercury released from amalgam fillings causes clinically detectable health effects (4–7) or diseases other than local allergic reactions (8, 9). The public concern about possible health effects from mercury released from amalgam restorations (10) is one of the main reasons why the Norwegian health authorities have given considerable atten- tion to possible adverse effects from dental mate- rials. In 2003, the Norwegian Directorate for Health and Social Affairs presented new guidelines for the use of dental restorative materials (11). It was stated that amalgam never should be the first material of choice, and from 2008, the use of dental amalgam was prohibited. Questions have been raised about potential risks to the fetus from prenatal exposure to mercury from amalgam fillings in pregnant women (12–15). It is known that mercury in the body of a pregnant woman is transferred to the fetus via the placenta and the umbilical cord blood (16). Mercury can also be transmitted via human milk (17–19). Studies have shown that fetal hair mer- cury concentration was significantly higher in babies when the mothers had been exposed to dental amalgam either before or during pregnancy compared to unexposed babies (20, 21). However, Community Dent Oral Epidemiol 2010; 38: 460–469 All rights reserved Ó 2010 John Wiley & Sons A/S Exposure to dental amalgam restorations in pregnant women Lygre GB, Bjo¨ rkman L, Haug K, Skjærven R, Helland V. Exposure to dental amalgam restorations in pregnant women. Community Dent Oral Epidemiol 2010; 38: 460–469. Ó 2010 John Wiley & Sons A ⁄ S Abstract – Objectives: 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. Methods: 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. Results: 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. Conclusion: Age, education, smoking habits, and BMI were associated with amalgam exposure. Gunvor Bentung Lygre 1 , Lars Bjo¨rk- man 1,2 , Kjell Haug 3 , Rolv Skjærven 3 and Vigdis Helland 1 1 Dental Biomaterials Adverse Reaction Unit, Uni Health, Bergen, Norway, 2 Department of Clinical Dentistry, University of Bergen, Norway, 3 Department of Public Health and Primary Health Care, University of Bergen, Norway Key words: amalgam fillings; children’s health; cohort; life style; pregnancies Gunvor Bentung Lygre, Dental Biomaterials Adverse Reaction Unit, Uni Health, A ˚ rstadveien 17, N-5009 Bergen, Norway Tel.: +47 55 58 60 27 Fax: +47 55 58 98 62 e-mail: Gunvor.Lygre@odont.uib.no Submitted 27 November 2009 accepted 15 January 2010 460 doi: 10.1111/j.1600-0528.2010.00544.x