Pregnancy nutrition 101: what to eat, what to avoid, and how to build a healthy baby
There is something incredible about pregnancy and the ability of our bodies to literally build and create another human. The biological and physiological processes that occur over the course of a human pregnancy are dramatic and require an incredible amount of energy and nutrients.
In fact, research continues to confirm that the foods you eat and the way you nourish your body during pregnancy has a direct impact on your baby’s health, not only in early infancy (1), but potentially for the rest of his or her life (2,3).
This is why nutrition during pregnancy is so important.
And yet, our healthcare system is not meeting the needs of pregnant and breastfeeding women. Even though women frequently report wanting more nutrition education (4) , more often than not, they are given the bare minimum in information and recommendations from clinicians who have minimal nutrition knowledge and training and express a lack of confidence in their ability to provide effective nutrition and weight counseling to pregnant women (5,6,7).
Registered dietitians are healthcare professionals that are THE experts in the use of food and nutrition to promote health and manage conditions, including pregnancy, from a clinical perspective, but seeing a registered dietitian is not a part of standard prenatal care in the United States.
This lack of coordinated care leaves many pregnant women to turn to google for their information, which can be filled with misleading or fear-based nutrition information, adding unnecessary and additional stress to moms who are just trying to do their best and figure out what they need to do during pregnancy.
When it comes to optimal pregnancy nutrition, the amount of information can seem overwhelming, but it really comes down to a few key factors that, if optimized, will set you and your baby up for success.
Fundamentals of a healthy pregnancy
At the most basic level, optimal pregnancy nutrition does not differ too much from optimal nutrition in your everyday life. You want to choose nutrient-dense foods, meaning foods that have a high level of nutrition (vitamins, minerals, antioxidants, phytochemicals) relative to their caloric value.
These foods tend to be things like vegetables, particularly cruciferous and green leafy vegetables, fruits, eggs, salmon and other fatty fish, quality meats, nuts and seeds.
Honestly, if you focus on making those food items the bulk of your diet during pregnancy, you are well on your way to eating optimally with few other things to worry about.
When choosing meal options, aim to get a protein source at each meal and snack (remember: your body is literally growing another organ and a whole person and will require a ton of protein for that). Also aim for high quality fat sources, which include fats that are higher in Omega-3 fatty acids (important for baby’s neural development). These include foods like fatty fish, grass-fed meats, eggs, nuts and seeds, avocado, and coconut.
Micronutrients are the vitamins and minerals that are essential for healthy development and the physiological processes that occur in our body. There are some micronutrients that are of particular importance during pregnancy for various reasons, and many, which increase in need during this time. Those include folate, iron, calcium, vitamin D, vitamin B12, vitamin B6, choline, glycine, vitamin A, vitamin K2, vitamin C, DHA, zinc, and iodine.
The majority of these can be obtained through a nutrient-dense diet, as discussed above. The more you eat foods that contain these vitamins and minerals, the less of a need you will have for external supplementation.
There are times during pregnancy where it can be tough to eat high nutrient foods, like in the first trimester when you’re dealing with morning sickness and fatigue. At these times and throughout pregnancy, a high-quality prenatal vitamin can be incredibly helpful to cover the gaps in your diet.
In addition to an increased need for nutrients, fluid needs also increase during pregnancy in order to support fetal circulation, amniotic fluid, and a higher blood volume. When you’re pregnant you want to aim for about 100oz of fluids daily.
I know that seems like a lot.
But fluid doesn’t just mean water. That’s total fluid intake for the day. Here are some things, besides water, that count as fluids: smoothies, soups, chilis, and broths, water-rich foods like watermelon, grapes, lettuce, or pickles, ice cream or popsicles, sauces and gravies, and obviously all the other drinks like milk or tea or juice.
Everyone is different and needs are different during pregnancy. It is possible to get most of your needs through a very nutrient-dense diet with food, but that’s not the case for most of us. Generally, in addition to a high-quality prenatal vitamin, some pregnant women may choose to also take a vitamin D supplement and an Omega-3, particularly DHA supplement.
Vitamin D is a really important nutrient that can prevent pregnancy complications and significantly impact the short-term and long-term health of your baby. But it’s pretty hard to get from our food and a lot of us don’t get great sun exposure. And studies estimate vitamin D deficiency is high in pregnant women - anywhere from 28-85% depending on where you live. Because of this, I usually suggest supplementing with Vitamin D.
DHA is absolutely essential for healthy brain development in your growing baby. It’s incorporated into the brain, eyes, and protects the brain from inflammation and other damage. It’s possible to meet your DHA needs through food if you’re consuming 2-3 servings of nutrient-rich seafood each week. But many of us aren’t doing that, so a supplement can help. If you are opposed to fish oil supplements, you can take an algae-based DHA supplement.
Those are really the main supplements that I have found to be most helpful for pregnant individuals. Others that may be helpful in certain situations are iron, probiotics, and magnesium.
Foods to Avoid During Pregnancy
The long list of things to not eat during pregnancy, almost always with few exceptions, are because of the risk of foodborne illness from things like parasites or bacteria. When you’re pregnant your risk of foodborne illness increases (), so it is important to be mindful of good food safety practices and avoid foods likely to harbor bacteria or parasites during this time.
Additionally, there are also foods that do not pose a food safety risk, but are also not providing optimal nutrition for you or your baby. Rather than strictly avoiding these foods, it is usually best to limit them as best you can.
Below are the foods (and non-foods) I would recommend completely avoiding during pregnancy based on risk and health:
Alcohol - no amount of alcohol has been shown to be safe during pregnancy and it will likely affect each of us differently, so it’s best to avoid it.
Energy drinks - This is a broad recommendation and perhaps there are exceptions, but they tend to have a lot of caffeine, a lot of added vitamins, and a lot of random ingredients where the safety hasn’t been assessed in pregnancy.
High mercury fish - like shark, bigeye tuna, king mackerel, and swordfish.
Raw shellfish - 85% of seafood illness comes from eating raw shellfish, basically raw mussels, oysters and clams
Undercooked pork, lamb, venison, and ground beef - toxoplasmosis gondii is a much higher risk in these cuts of meat than it is in beef.
Soft cheese from unpasteurized milk - it’s 50-160X more likely to cause Listeria infection than when it’s pasteurized. And in the United States, we pasteurize the majority of our cheese, so there are a lot of great alternatives for you to choose from.
And these are the foods that I would work to limit - not necessarily avoid completely - but limit in pregnancy.
Remember: your goal when it comes to eating in pregnancy is to get optimal nutrients and energy for your growing baby. So with that in mind:
Caffeine - stick to the guidelines of under 200mg daily on most days.
Refined carbohydrates - they just don’t have a lot of nutrients, so the more you eat, the less nutrition you’re taking in for your baby. They also have a major impact on blood glucose, and can increase your risk or worsen your symptoms of gestational diabetes.
Straight refined sugar from sources like soda, candy, and juice. This is for the same reason as refined carbohydrates. Just try to limit the amount as much as possible.
Low quality fats (vegetable oils, processed seed oils, trans fats - which will say partially hydrogenated in the ingredient list). The quality of fat can have an impact on cognitive development in your baby, so try to get fat from high quality sources - like avocados, eggs, fatty fish, and quality meat. You might also want to consider taking a DHA supplement if you do not eat a lot of these food sources.
It is important to point out that these are recommendations for an optimal pregnancy diet. The human body is pretty incredible and even when conditions aren’t optimal, will do everything it can to bring a healthy baby to term.
There are a number of things that can happen during pregnancy that make eating optimally difficult or seemingly impossible. For example, nausea, vomiting, and food aversions that are common in the 1st trimester, but can last an entire pregnancy for some women. During these times, the first priority is really to manage the symptoms and accept that you might not be able to eat optimally during that time. And that’s ok. Just make sure to find windows of times to fit in nutrient-dense foods when you can and don’t stress too much when you can’t.
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.