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3 Myths About Nutrition During Pregnancy

Updated: Aug 13, 2022

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.

There is enough we need to be concerned about as we navigate our pregnancies without the added stress and anxiety that comes with dietary misinformation for pregnant and breastfeeding women. So, let’s go over a few of the top dietary myths during pregnancy that I came across, so that you can eat well and feel great for that perfect little human you are working to grow.

You Need to “Eat for Two”

The concept of “eating for two” is not necessarily wrong. We do need to consider that there is a baby (the #2) that is growing and will need nourishment. But the concept is pretty much universally misinterpreted to mean that we need to eat double the quantity of food - which is definitely not the case.

Our body does not actually need that many more calories when pregnant. In fact, it’s often cited that women do not need any additional calories during the first trimester, and only a minimal increase in calories (~300 calories/day) after the first trimester. However, research continues to indicate that this is just an average and could even be overestimated for many women depending on a number of factors including pre-pregnancy weight, body fat percentage, activity level, and others (1).

In any case, even if we do go with the 300 calorie average, that’s only the equivalent of adding an extra snack in our day - a banana with 2TB of peanut butter or a 6oz container of yogurt and 1/2 cup granola - not double the portions.

What does increase, however, is our body’s need for certain nutrients like folate, vitamin B12, iron, vitamin A, and many others. So, while we certainly don’t need a lot more food, we should try and ensure that we are optimizing the nutrient density of our diets and consuming foods that have an abundant amount of vitamins and minerals. Think quality over quantity.

You Need to Cut Out Caffeine

When it comes to caffeine intake during pregnancy, the most commonly articulated fears are an increased risk of miscarriage and preterm birth. Admittedly, the research on caffeine during pregnancy is not conclusive and is limited by small sample size, confounding factors that don't allow us to assess causality, and retrospective collection of data influenced by recall bias (2, 3, 4).

What is much more clear is that caffeine intake amounting to about 200mg per day is almost certainly safe during pregnancy. In fact, nearly all official governing bodies, including the American College of Obstetricians and Gynecologists (ACOG) and the World Health Organization (WHO) suggest that caffeine up to 200mg per day is safe (5). That’s the equivalent of about two 8-oz cups of coffee, depending on brewing methods.

It is worth mentioning that this is a very conservative estimate. There are almost no high-quality studies suggesting that caffeine intakes above this are harmful or cause preterm births or increased miscarriage. Even ACOG, states that they are unable to find a correlation between high caffeine intake and miscarriage. But for now, until the evidence is stronger, this is the most reliable recommendation that we have.

When I was pregnant, I switched from coffee to Americanos, so that I could better assess the amount of caffeine I was taking in each day. Each shot of espresso is equivalent to about 75mg of caffeine, so I had one Americano in the morning and one in the afternoon and never gave it a second thought.

You Need to Give Up 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 “Do not eat sushi made with raw fish (cooked sushi is safe).”

But why?

There are really 2 specific reasons for this recommendation: food-borne 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

Some fish are actually quite high in mercury, but 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. The best predictor of mercury content is the size of the fish, so if anything, you may want to avoid large amounts of tuna, swordfish, shark, tilefish, 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, anchovies, cod, haddock, hale, or trout.

Food-borne Illness

The main reason sushi is considered an off-limits food during pregnancy is because of the risk of food-borne illness. However, flash freezing, which is done to the vast majority of restaurant-grade sushi, is effective for killing any parasites. Furthermore, seafood for human consumption undergoes screening for microbial contamination, thus increasing safety.

And even more, if you actually look at the data of food-borne illness in the United States, raw fish is not even one of the highest contributors.

A recent CDC report that assessed food sources of food-borne 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 (6). In fact, studies suggest that nearly 50% of all food-borne illness in the US comes from produce. And yet we’re not asking women to give up fruits and vegetables during pregnancy.

The more you look into the data on food-borne 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. 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 (7)

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.

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Jessica Knurick is a Registered Dietitian with a PhD in physical activity, nutrition, and wellness, and has spent the last decade working on the wellness side of healthcare in the research lab, in clinical care, and with innovative medical tech startups aimed at improving the health of individuals on a person-centered, ongoing basis. Jessica is also the co-founder of Kula Inc., an online platform that is transforming the way moms receive support.

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