Fish Consumption During Pregnancy, Prenatal Mercury Exposure, and Anthropometric Measures at Birth in a Prospective Mother-Infant Cohort Study in Spain

Abstract

Previous studies suggested that there may be an association between birth size and the type and amount of fish consumed during pregnancy. One study suggested an inverse association between fetal growth and fatty fish but not lean fish. No association between mercury exposure and birth size has been reported. The aim of this population-based cohort study was to investigate the effect of the different types of fish consumed in late pregnancy on prenatal mercury exposure and to assess the association of the type of fish consumed and corresponding mercury exposure with birth weight, birth length, and classification as small for gestational age (SGA) in newborn infants. The association between total cord blood mercury and consumption of different types of fish by pregnant women was determined in 554 singleton live-born infants for several birth outcomes. For each subject, the frequency of fish consumption in the different fish groups was placed into 1 of 4 categories (<1 portion/mo, 1–3 portions/mo, 1 portion/wk, and ≥2 portions/wk). Multivariate analysis showed that newborns in the highest quartile of total mercury weighed 143.7 gm less (95% confidence interval [CI]: −251.8–35.6) than those in the first quartile (P for trend = 0.02), and also had an increased likelihood of having an SGA birth length, with an odds ratio of 5.3 (95% CI: 1.2–23.9; likelihood ratio test, P = 0.03) but with no linear relation (P for trend = 0.13). Mothers who consumed ≥2 portions/wk of canned tuna had offspring with higher birth weights than mothers who consumed <1 portion/mo (P for trend = 0.03), and had a lower risk of having an infant with an SGA weight (P for trend = 0.01). Women who consumed ≥2 portions of lean fish/wk had a lower risk of having an infant who was SGA for length compared with those who ingested <1 portion/wk, and consumption of ≥2 portions/wk of large oily fish was associated with an increased risk of an infant who was SGA for weight, but these associations were not statistically significant (P for trend >0.05). These findings show that the amount and type of fish consumed during pregnancy may influence fetal growth and other birth outcomes.