Maternal Fish Consumption, Mercury Levels, and Risk of Preterm Delivery

Abstract

BackgroundPregnant women receive mixed messages about fish consumption in pregnancy because unsaturated fatty acids and protein in fish are thought to be beneficial, but contaminants such as methylmercury may pose a hazard.MethodsIn the Pregnancy Outcomes and Community Health (POUCH) study, women were enrolled in the 15th to 27th week of pregnancy from 52 prenatal clinics in five Michigan communities. At enrollment, information was gathered on amount and category of fish consumed during the current pregnancy, and a hair sample was obtained. A segment of hair closest to the scalp, approximating exposure during pregnancy, was assessed for total mercury levels (70–90% methylmercury) in 1,024 POUCH cohort women.ResultsMercury levels ranged from 0.01 to 2.50 μg/g (mean = 0.29 μg/g; median = 0.23 μg/g). Total fish consumption and consumption of canned fish, bought fish, and sport-caught fish were positively associated with mercury levels in hair. The greatest fish source for mercury exposure appeared to be canned fish. Compared with women delivering at term, women who delivered before 35 weeks’ gestation were more likely to have hair mercury levels at or above the 90th percentile (≥ 0.55 μg/g), even after adjusting for maternal characteristics and fish consumption (adjusted odds ratio = 3.0; 95% confidence interval, 1.3–6.7).ConclusionThis is the first large, community-based study to examine risk of very preterm birth in relation to mercury levels among women with low to moderate exposure. Additional studies are needed to see whether these findings will be replicated in other settings.

Interaction between GSTM1/GSTT1 Polymorphism and Blood Mercury on Birth Weight

“…Information on fish consumption was collected using 24-hr recall, which can result in recall bias and may not reflect dietary intake during the entire period of pregnancy. However, there did not appear to be any differential recall bias, because the dietary survey was carried out before the pregnancy outcome (Xue et al 2007). In this study, the total Hg level in maternal and cord blood was assessed.…”

Comparison of a toxicokinetic and a questionnaire-based approach to assess methylmercury intake in exposed individuals

“…The corresponding MeHg concentrations were calculated considering that 90% of total mercury in fish is found in the methylated form (WHO, 1990;Cabanero et al, 2007;Xue et al, 2007;Mieiro et al, 2009) …”

“…The statistical software SPSS 16.0 was used for this purpose (SPSS Software, Chicago, IL, USA). Calculated MeHg concentration in seafood considering that 90% of total mercury in fish is in the methylated form (Cabanero et al, 2007;Xue et al, 2007). MeHg concentration in mg/g ¼ 0.9  total Hg concentration in mg/g  molecular weight MeHg (215.62)/molecular weight Hg (200.59).…”

Collate the literature on toxicity data on mercury in experimental animals and humans (Part I – Data on organic mercury)

“…Lucas et al (2004) did also not observe a decrease in gestational age at even higher mercury levels in cord plasma (about 154 µg/L). As the observations from Xue et al (2007) are only based on few cases no definite conclusions can be drawn from these findings currently. ALA-D activity in total blood 5)…”

“…The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. Xue et al (2007) reported an increase in preterm deliveries at even lower hair concentrations (mean: 0.29 µg/g, convertible to a cord blood level of 1.45 µg/L). They only found a significantly increased risk for very early preterm deliveries (< 35 weeks), but not for preterm deliveries at later time points (35-36 weeks).…”