There were a lot of things that surprised me after I became pregnant for the first time. The ridiculously frequent trips to the bathroom starting early in my first trimester, the exhaustion like I had never experienced, and the number of people who all of a sudden felt comfortable touching me or commenting on my body (what is with that?) to name a few. But as a dietitian with a PhD in nutrition, probably the most surprising thing to me was the incredible amount of misinformation, and, I assume, well meaning pregnancy nutrition advice that had little to no supporting evidence or data.
Let’s discuss the one that mattered the most to me: sushi.
The official recommendation in the United States, contrary to Japan, the UK, Australia, and others, is to avoid all raw or undercooked seafood while pregnant. ACOG even explicitly states “You should avoid all raw or undercooked fish when you’re pregnant” (1).
But why?
There are really 2 specific reasons for this recommendation: foodborne illness (from listeria, salmonella, or parasites) and mercury poisoning (mercury is a neurotoxin and the fear is that it could harm brain development). Let’s take a look at both.
Mercury Poisoning
Mercury is a neurotoxin and very high doses in pregnancy can cause hearing, vision, and cognitive impairment in the child (2). Since the Minamata incident in Japan in 1956 (3), the public has become increasingly aware and concerned about environmental pollution affecting the seafood supply and the resulting negative health consequences.
While some fish are actually quite high in mercury, many, even most, fish are perfectly safe to eat during pregnancy, not only because they are low in mercury, but also because the fish contain high levels of selenium, which binds to mercury and prevent it from doing damage to the body (4). In fact, research consistently shows positive effects of regular fish intake during pregnancy on children’s IQ, communication skills, fine motor skills, and cognitive abilities (5, 6, 7, 8, 9).
The best predictor of mercury content is the size of the fish, so if anything, you may want to avoid large amounts of some tuna, swordfish, shark, tilefish, marlin, orange roughy, king mackerel, and marlin. But there doesn’t appear to be any reason, with regard to mercury, to avoid fish like salmon, whitefish, catfish, cod, haddock, hale, trout, and many others (Use the guide here).
Foodborne Illness
The main reason sushi is considered an off-limits food during pregnancy is because of the risk of foodborne illness. However, flash freezing, which is done to the vast majority of restaurant-grade sushi, is effective for killing any parasites (10). Furthermore, seafood for human consumption undergoes screening for microbial contamination, thus increasing safety.
And even more, if you actually look at the data of foodborne illness in the United States, raw fish is not even one of the highest contributors.
A recent CDC report that assessed food sources of foodborne illness from high priority pathogens (including salmonella and listeria) showed that for salmonella, 38% of all cases were found in vegetables and fruits, and eggs and meats made up nearly 40% of all cases. And for listeria, 50% of all cases came from fruits and 31% from dairy (11). In fact, studies suggest that nearly 50% of all foodborne illness in the US comes from produce (12). And yet we’re not asking women to give up fruits and vegetables during pregnancy.
The more you look into the data on foodborne illness, the more you start to realize how arbitrary some of these recommendations really are.
There is a cost to these recommendations to avoid fish too. The nutrients in fish are incredibly beneficial to pregnant women and their babies. Fish contains omega-3 fatty acids, important for babies brain development, and many incredibly important vitamins and minerals, including vitamins D, B6, and B12, iron, iodine, zinc, and selenium. Not to mention, it is an excellent source of protein. To reiterate the benefits explained above, in one study of over 12,000 mother-infant pairs, more than 12oz of fish consumption was strongly linked to childhood IQ and communication skills, and mothers who ate no fish during pregnancy had children who were more likely to have problems with fine motor skills, social development, and communication skills (13).
When I was pregnant, I researched the heck out of this topic because I love sushi, but I also wanted to make sure I was doing everything I could to keep my baby as healthy as possible. For me, the data and recommendations didn’t add up and the benefits of eating fish, outweighed the potential negative effects. I ate sushi occasionally from reputable restaurants that I went to before getting pregnant without ever getting sick.
As with everything, you get to make the best decision for you and your baby, but I do think it’s important that we have the correct information to make educated decisions when it comes to our health.