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Public Health Nutr. 2014 Sep;17(9):2071-80. doi: 10.1017/S1368980013002619. Epub 2013 Oct 8.

Prenatal mercury exposure and infant birth weight in the Norwegian Mother and Child Cohort Study.

Author information

1Division of Epidemiology,Norwegian Institute of Public Health,Post Box 4404 Nydalen,NO-0403 Oslo,Norway.
2Division of Environmental Medicine,Norwegian Institute of Public Health,Oslo,Norway.
3Office of Director-General,Norwegian Institute of Public Health,Oslo,Norway.



To examine the association between calculated maternal dietary exposure to Hg in pregnancy and infant birth weight in the Norwegian Mother and Child Cohort Study (MoBa).


Exposure was calculated with use of a constructed database of Hg in food items and reported dietary intake during pregnancy. Multivariable regression models were used to explore the association between maternal Hg exposure and infant birth weight, and to model associations with small-for-gestational-age offspring.


The study is based on data from MoBa.


The study sample consisted of 62 941 women who answered a validated FFQ which covered the habitual diet during the first five months of pregnancy.


Median exposure to Hg was 0·15 μg/kg body weight per week and the contribution from seafood intake was 88 % of total Hg exposure. Women in the highest quintile compared with the lowest quintile of Hg exposure delivered offspring with 34 g lower birth weight (95 % CI -46 g, -22 g) and had an increased risk of giving birth to small-for-gestational-age offspring, adjusted OR = 1·19 (95 % CI 1·08, 1·30). Although seafood intake was positively associated with increased birth weight, stratified analyses showed negative associations between Hg exposure and birth weight within strata of seafood intake.


Although seafood intake in pregnancy is positively associated with birth weight, Hg exposure is negatively associated with birth weight. Seafood consumption during pregnancy should not be avoided, but clarification is needed to identify at what level of Hg exposure this risk might exceed the benefits of seafood.

[Indexed for MEDLINE]

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