Fish and seafood during pregnancy can feel confusing because women often hear more about mercury risks than about nutritional benefits. But research suggests that suitable fish and seafood can provide important nutrients for a baby’s brain and eye development. This blog explores why the guidance may need to become more balanced.
There is so much confusion around what women should and shouldn’t eat during pregnancy.
One area that seems to cause a lot of worry is fish and seafood.
Many pregnant women are told to be careful with fish because of concerns about mercury and other contaminants. Of course, food safety in pregnancy matters, and there are certain fish that should be avoided. But I recently attended a FAB Research webinar called Fish and Seafood During Pregnancy: Why New Guidance is Urgently Needed, and it really highlighted an important question:
Are we focusing so much on the possible risks of fish that we are forgetting to explain the benefits?
Why fish matters during pregnancy
Fish and seafood are not just a source of protein. They provide a unique combination of nutrients that are particularly important for a baby’s developing brain and eyes.
This matters because pregnancy is a critical window for brain development. Around 70% of fetal brain cells develop before birth, which means the nutrients a baby receives during pregnancy can have a significant impact on brain development.
This period of rapid brain-building is known as neurogenesis, during which new brain cells are created at an extraordinary pace. Because cell division and brain structure formation occur so quickly, the demand for key nutrients such as DHA, iodine, choline, protein, iron, zinc, and B vitamins is especially high.
One of the key nutrients is DHA, an omega-3 fatty acid that is needed for normal brain development. During pregnancy and early life, the baby’s brain is developing rapidly, so the mother’s intake of these nutrients can be really important.
Reaching an optimal intake of omega-3 DHA for brain development can be difficult from food alone if fish and seafood are not included, because they are the richest natural dietary sources. This is one reason why simply advising women to limit or avoid fish, without discussing suitable alternatives, may leave an important nutrient gap.
But fish and seafood offer much more than omega-3. They also contain iodine, selenium, zinc, vitamin D, vitamin A, B vitamins, choline and complete protein. These nutrients all play different roles in brain development, thyroid function, immune health, cell signalling, energy production and neurotransmitter function.
This is why fish is sometimes described as a “whole food” for brain development. It is not just one nutrient in isolation. It is the combination of nutrients working together.
Have we made women too scared of fish?
For years, the main message many women have heard is to limit fish because of mercury. This has made many women nervous, and some avoid fish completely during pregnancy.
The concern raised in the FAB Research webinar is that this may have unintended consequences.
If women avoid fish and seafood but do not replace those nutrients in another meaningful way, their babies may miss out on nutrients that are difficult to obtain from other foods. This is particularly important because pregnancy is such a critical window for brain development.
The webinar highlighted that current advice may have led pregnant women to reduce or eliminate one of the most beneficial whole foods for prenatal brain development. It also shared the view that the overall evidence points towards a clear net benefit from fish and seafood consumption in pregnancy.
That does not mean women should eat any type of fish without thinking. It means the guidance needs to be clearer and more balanced.
What does the evidence suggest?
The key message from FAB Research is that the benefits of regular fish and seafood consumption in pregnancy appear to outweigh the hypothesised risks.
The FAB handout explained that systematic reviews of prospective population studies have found benefits of fish and seafood consumption during pregnancy, particularly for children’s cognitive development.
The webinar also noted that no studies have found neurodevelopmental harm from maternal fish consumption, regardless of the amount consumed. In contrast, higher fish and seafood intake has been associated with better neurodevelopmental outcomes, including higher IQ.
This is an important distinction.
We need to move away from messaging that only says “be careful” and towards messaging that helps women understand:
- Why fish and seafood can be beneficial
- Which fish are safer choices
- Which fish should be avoided
- How to meet omega-3 and other nutrient needs if they decide not to eat fish
We can also look at traditional Japanese dietary patterns, where fish and seafood are eaten regularly and often form a central part of the diet. Japan has one of the highest life expectancies in the world, and researchers have suggested that high fish intake, providing omega-3 fats, alongside other features of the traditional Japanese diet, may contribute to lower rates of heart disease and some of the most common cancers.
The nutrients in fish that support brain development
Fish and seafood provide a package of nutrients that is difficult to replicate from a single food source.
These include:
Omega-3 DHA and EPA
These are important structural and functional fats in the brain. DHA is especially important during pregnancy and early life.
Iodine
Iodine is needed to make thyroid hormones, which are vital for brain development and function. Iodine deficiency is one of the biggest preventable causes of brain development problems worldwide.
Vitamin D
Vitamin D supports bone health and immunity, but it is also involved in normal brain development and function.
B vitamins
B vitamins support energy production and chemical signalling in the brain. They are involved in attention, memory and mood regulation.
Zinc
Zinc is needed for immune regulation, growth, fertility and hundreds of biochemical reactions in the brain and body.
Selenium
Selenium supports antioxidant protection and is also relevant because it may help protect against mercury toxicity.
Vitamin A
Oily fish can provide pre-formed vitamin A, which is important for vision, immunity and cell signalling. This is one reason advice needs to be careful and individualised, because excess vitamin A from some sources is not advised in pregnancy.
Choline
Choline is important for brain cell membranes and acetylcholine, a neurotransmitter involved in memory, mood and mental function.
Protein
Fish provides a complete protein, supplying the amino acids needed to build and repair cells and to make neurotransmitters.
So what should pregnant women do?
The message is that women need better guidance.
Pregnant women should still avoid fish known to be higher-risk during pregnancy and follow relevant UK national safety advice. But they should also be told why suitable fish and seafood can be beneficial, rather than only hearing warnings.
A more helpful message would be:
“Fish and seafood can provide important nutrients for your baby’s brain and eye development. The key is choosing appropriate types of fish and eating them in a balanced way.”
For women who do not eat fish, it is important to consider how they will obtain DHA, iodine, choline, selenium, vitamin D, B vitamins and protein from other sources. This may involve dietary planning and, where appropriate, carefully chosen supplementation.
For vegetarians and vegans, this is especially important. Plant foods such as chia seeds, flaxseeds, hemp seeds and walnuts provide ALA, a plant-based omega-3 fat, but the body has to convert this into DHA and EPA, and this conversion can be limited. Algae-based omega-3 can be a useful option because it provides DHA directly without fish. It is also important to consider other nutrients commonly found in fish and seafood, including iodine, selenium, vitamin D, choline, B vitamins, and protein. I have written more about this in my blog on key nutrients to consider in vegetarian and vegan diets.
My view as a Registered Nutritionist
In clinic, I often see how easily food advice becomes fear-based, especially during pregnancy. Women are trying to do the right thing, but they are often given lists of what to avoid without enough explanation of what to include.
This is where nutrition guidance needs to be more practical and supportive.
We should not be making women feel anxious about food. We should be helping them understand how to nourish themselves and their babies well.
Fish and seafood can be a valuable part of a pregnancy diet when chosen appropriately. The current conversation needs to become more balanced, moving away from simply warning women about risk and towards helping them make informed, confident food choices.
Final thoughts
The evidence presented by FAB Research raises an important public health question:
Have we become so focused on the potential risks of fish that we are overlooking the risks of not eating it?
Pregnancy is a critical time for brain development, and fish and seafood provide a unique package of nutrients that are difficult to replace. Women deserve clear, evidence-informed guidance that explains both the benefits and the cautions.
As always, individual needs vary. If you are pregnant, planning pregnancy, a vegetarian or vegan, avoiding fish, or unsure about your nutrient intake, it is worth getting personalised nutrition advice.
Small changes in pregnancy nutrition can make a meaningful difference, not just for the mother’s health, but for the next generation, too. If you are pregnant, planning a pregnancy, or avoiding fish and seafood, I can help you understand how to meet your key nutrient needs safely and confidently through food, testing, and personalised nutrition support. You can book a discovery call here.
BOOK A FREE CallIf you are interested in exploring this topic in more depth, I would also recommend
“The Shrinking Brain” by Professor Michael Crawford and David Marsh.
Professor Crawford is one of the world’s leading experts on fatty acids, brain development and human evolution, and his work helps explain why nutrients from fish and seafood are so important for the developing brain.
This blog is for general education only and does not replace personalised medical or pregnancy advice from your midwife, GP and healthcare provider.
LINKS TO RESEARCH
FAB Research webinar/resource page
FAB Research article on omega-3 in pregnancy and preterm birth
