US and British scientists have shown that children whose mothers ate fish several times a week while they were pregnant were more likely to have higher scores in tests of mental and social ability.

The study is published in The Lancet.

The scientists sent questionnaires periodically to 11,875 pregnant women in Bristol, England who were part of the Avon Longitudinal Study of Parents and Children (ALSPAC) and whose babies were expected to be born between April 1991 and December 1992.

The mothers were asked questions about their diet during pregnancy and about their children’s mental and social development up to the age of 8.

The researchers noted that “children of mothers who ate small amounts of seafood were more likely to have suboptimum neurodevelopmental outcomes than children of mothers who ate more seafood”.

Using multivariable logistic regression analysis the researchers compared the children’s developmental, behavioural and cognitive scores against their mothers’ seafood consumption in pregnancy. The mothers’ sea food consumption was in three categories: no seafood consumed, some seafood consumed (up to 340 g per week), and seafood consumption exceeding 340 g per week.

The analysis took into account and eliminated 28 other factors or confounders that might have had an impact, such as social disadvantage and dietary habits.

The results showed that where mothers had consumed less than 340 g a week, this was linked to a significant increased likelihood that their children would be in the bottom 25 per cent of verbal intelligence quotient (IQ) at age of 8, and to have “suboptimum performace” on developmental and social behaviour tests. This was in comparison to children whose mothers ate more than 340 g of seafood a week.

The study was led by Dr Joseph Hibbeln of the US National Institute of Alcohol Abuse and Alcoholism. He said that “For the baby’s development, at the level of 12 ounces (340 g) a week during pregnancy, the beneficial effects of the nutrients in fish far outweigh the risk.”

340 g a week (about 12 ounces, equivalent to three servings) is the most seafood a pregnant woman is advised to eat in the US because of risks associated with toxic elements such as mercury. This is the advice of the Food and Drug Adminstration (FDA) and the Environmental Protection Administration (EPA).

The EPA and the FDA are aware of the study and say they have no plans to change their advice at this stage.

The researchers said they had problems finding a large group of American women who ate fish several times a week which is why they used the English cohort.

While the study did not look into the reason why maternal fish eating might confer advantages to the child’s development, the researchers speculated that it might be due to the high levels of omega-3 fatty acids in seafood. These long chain fatty acids are considered essential for neurological development in pregnancy and early childhood.

Omega-3 fatty acids are also present in other foods such as hemp seeds, chia seeds, flax seeds, walnuts, kiwi fruit and eggs from chickens whose diet includes greens and insects.

“Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study.”
Joseph R Hibbeln, John M Davis, Colin Steer, Pauline Emmett, Imogen Rogers, Cathy Williams and Jean Golding.
The Lancet 2007; 369:578-585

Click here for full text of Article.

Click here for more information on diet during pregnancy (Food Standards Agency, UK).

Written by: Catharine Paddock
Writer: Medical News Today