Objectives: The purpose of this study was to estimate the amount of absorbed mercury (Hg) by mothers and their infants as a result of fish consumption during pregnancy.
Materials and methods: The cohort consisted of 313 mother-infant pairs recruited initially from ambulatory prenatal clinics in the first and second trimesters of pregnancy. The customary pattern of fish consumption during pregnancy reported by mothers was correlated with Hg levels in cord and maternal blood at delivery. Blood Hg level was measured using atomic absorption spectrometry.
Results: The mean Hg concentration in cord blood was markedly higher than in maternal blood at delivery (1.09 microg/L; 95%CI: 1.00-1.13 microg/L vs. 0.83 microg/L, 95%CI: 0.76-0.91 microg/L). There was significant correlation (r(s)=0.62, 95%CI: 0.55-0.69) between Hg levels in cord and maternal blood. The overall ratio of Hg in cord blood vs. maternal blood was 1.7 (95%C: 1.50-1.89). Fish consumed during the last pregnancy trimester correlated stronger with umbilical cord concentrations (r(s)=0.32; 95%CI: 0.22-0.40) than with Hg in maternal blood (r(s)=0.23; 95%CI: 0.14-0.33).
Conclusions: The study shows that in Poland, babies are exposed to moderate levels of mercury prior to birth and that fish eating in pregnancy significantly contributes to prenatal Hg exposure. The findings also suggest that the level of cord blood Hg should not be used for describing inter-individual differences in maternal exposure to Hg unless a proper correction factor is introduced.