Pregnant women should eat more fish to boost the development of their children, new research suggests. They are usually advised to steer clear of oily fish amid fears the build-up of mercury can damage the brain of babies in the womb.
But Swedish scientists, using data from nearly 39,000 mothers and their children, have found eating seafood during pregnancy only benefits children.
Children born to mothers who consumed 400g of oily fish each week while they were expecting had higher language and communication skills.
However, the researchers warned pregnant women should avoid eating anymore than this amount due to the potential effects of mercury.
How was the study carried out?
For the new study, researchers obtained blood samples from a small group of 2,239 women in week 17 of gestation.
Prenatal mercury exposure was also calculated by asking all of the 38,581 women to report what they consumed halfway through their pregnancy.
Mothers then reported children’s language and communications skills at age five by filling out a questionnaire.
The scientists at the Norwegian Institute of Public Health, Oslo, then performed a statistical analysis to assess the impact of mercury.
For mothers who ate less than 400g of seafood a week there were clear benefits, they reported in the journal Environment International.
Such children performed significantly better on the speech and language test, the researchers found.
They added ‘maternal seafood intake during pregnancy was positively associated with the language and communication scales’.
Authorities in the US changed their advice in June 2014 to limit fish consumption for pregnant or breastfeeding women to no more than three servings a week.
The decision, undertaken by the Food and Drug Administration, was made in light of evidence about pollutants.
The authority issued clearer advice for pregnant women in January as to what fish they can eat safely, and which to avoid.
The guidance in the UK
The NHS encourages pregnant women to eat fish because of the benefits of omega-3 fatty acids.
However, it says swordfish, shark and marlin should be completely avoided because of high mercury levels.
Consumption of tuna, which contains moderate levels of mercury, should be limited to two steaks a week or four cans, the NHS says.
It also says that pregnant women should also eat no more than two portions a week of oily fish such as mackerel, sardines or salmon.