Decreased birthweight among infants born to women with a high dietary intake of fish contaminated with persistent organochlorine compounds

OBJECTIVES: The purpose of the study was to assess reproductive outcomes, especially birthweight, and the consumption of fatty fish from the Baltic Sea, contaminated with persistent organochlorine compounds, among women from the Swedish east coast.

MATERIAL AND METHODS: Cohorts of fishermen's wives from the Swedish east and west coasts were established and linked to the Swedish Medical Birth Register for 1973-1991; 1501 children were born in the eastcoast cohort and 3553 in the westcoast cohort. Comparisons were made with regional populations and between the cohorts. Dietary interviews were made with 69 randomly selected women from the cohorts and 69 referents.

RESULTS: The women interviewed from the east- and westcoast cohorts ate locally caught fish more than twice as often as their referents. Compared with the regional population, the women in the eastcoast cohort gave birth to an increased number of infants with low birthweights (< 3000 g), whereas the opposite was seen in the westcoast cohort. Infants in the eastcoast cohort had significantly lower birthweights than infants from the westcoast cohort (median 3530 versus 3610 g, P < 0.001). Even after adjustment for potential confounders, eastcoast affiliation showed an increased risk for low birthweight (odds ratio 1.44, 95% confidence interval 1.18-1.76). The effect was more conspicuous for boys (odds ratio 1.95) and heavy smokers (odds ratio 3.00).

CONCLUSIONS: The present data support, but do not prove, an association between a high consumption of contaminated fish from the Baltic Sea and an increased risk for low birthweight.