As soon as women find out they’re pregnant, they are overwhelmed with information about what they can – or more likely can’t – eat and drink. Off the menu go soft cheeses, partially cooked eggs, raw meat, pâté, liver, caffeine, alcohol. It’s a lot to remember.
But the advice on eating fish when pregnant is the by far the most complex. Does it need to be so complicated? What is the actual evidence of the risks and benefits of eating fish for a mother-to-be?
The UK Food Standards Agency, through NHS Choices, gives advice to pregnant and breastfeeding women, as well as women planning to become pregnant. It focuses on the consumption of mercury and chemicals known as polychlorinated biphenyls (PCBs) and dioxins in fish and seafood.
The guidelines for women planning to become pregnant and pregnant women include three fish to avoid completely. These are the predatory species, marlin, shark and swordfish. There is also information on limiting intake of other fish, such as fresh and canned tuna.
The guidelines for women who are breastfeeding differ slightly. For them, predatory fish are allowed once a week and there is no limit on canned tuna.
Crucially, the guidance also includes a recommendation to eat at least two portions of fish a week, at least one of which should be oily – important advice that is mentioned only in passing on the NHS Choices web page.
It all adds up to a complicated set of advice. To be able to follow it, women are required to distinguish correctly between different species of fish. They need to be able to identify oily fish and to keep a weekly tally of the number of portions of different species they have eaten.