Having a little seafood if you’re pregnant (but still watching out for the mercury, of course) may protect against depression, new research finds. The study, published in the July issue of the journal Epidemiology, followed almost 10,000 women in Britain and questioned them about their seafood habits during pregnancy.

The study took place in 1991 and 1992, when seafood was the main source for omega−3 fatty acids (people were, in general, less aware of the many benefits and sources of fatty acids even as recently as the early 90s). The women were surveyed in week 32 of their pregnancies, answering questions about how much seafood they ate per week over the course of their pregnancies as well as questions about their mood while pregnant.

Depression during pregnancy not only affects the mother, but it can be damaging to the baby as well.

Women who ate no seafood at all were 50% more likely to suffer from depression while pregnant than women who ate seafood at least three times per week (the equivalent of about 1.5 of omega−3 fatty acids, the researchers calculated). When the team controlled for other variables that might confound (threaten the validity of) the relationship between seafood and mood, the findings still held strong, suggesting that there really is something to this link.

The authors point out that in countries where diets are rich in seafood, depression is nearly non−existent, in contrast to many Western countries. They also add that depression during pregnancy not only affects the mother, but it can be damaging to the baby as well.

In response to the long−standing recommendation that pregnant women limit the amount of mercury in their diets (and some fish are quite high in the element), the researchers say that "[i]t's possible that limiting intake in accordance with this advice could increase the risk of maternal depressive symptoms during pregnancy." The authors conclude that eating some seafood during pregnancy may have a benefit to “mental well−being,” but that more research needs to be devoted to the connection to flesh it out further.

The research was carried out at the University of Bristol, by a research team led by Jean Golding.