During the third trimester, your body needs roughly 2,400 calories per day, about 300 more than before pregnancy. But what matters more than the calorie count is where those calories come from. Your baby is gaining weight rapidly, building bones, and wiring a brain, all of which depend on specific nutrients hitting your plate consistently over these final weeks.
Why the Third Trimester Is Nutritionally Different
The last 13 weeks of pregnancy are when your baby does the most growing. Fetal bone mineralization peaks during this stretch, requiring 20 to 30 grams of calcium total for skeletal development. Your blood volume is at its highest, demanding more iron than at any other point in pregnancy. And your baby’s brain is rapidly maturing, making this a critical window for the fats and nutrients that support neuronal development.
All of this means the third trimester isn’t just about eating more. It’s about eating strategically, with an emphasis on nutrient-dense foods that serve double duty for you and your baby.
Protein: Building Blocks for Growth
You need about 71 grams of protein per day during the third trimester. That’s significantly more than the 46 grams recommended for non-pregnant women. Protein supports your baby’s rapid tissue growth and helps your body keep up with its own expanding blood supply and uterine tissue.
Lean meats, poultry, eggs, beans, lentils, tofu, and Greek yogurt are all reliable sources. Spreading protein across meals and snacks helps with absorption and keeps your energy steadier than loading it into one big dinner.
Iron: Keeping Up With Your Blood Supply
Pregnancy increases the volume of blood in your body substantially, and your body uses iron to produce the extra red blood cells that carry oxygen to your baby. The daily recommendation during pregnancy is 27 milligrams of iron, nearly double what’s needed outside of pregnancy.
Red meat, poultry, and shellfish provide the form of iron your body absorbs most efficiently. Plant sources like spinach, lentils, fortified cereals, and kidney beans work too, especially when you pair them with something rich in vitamin C (bell peppers, citrus, tomatoes) to boost absorption. Iron deficiency anemia is one of the most common complications in late pregnancy, so this nutrient deserves consistent attention.
Calcium for Fetal Bone Development
Your baby’s skeleton undergoes its heaviest mineralization during the third trimester, drawing calcium from your bloodstream at a high rate. If your diet doesn’t supply enough, your body will pull it from your own bones to meet fetal demand.
The daily target is 1,000 milligrams for women 19 and older, and 1,300 milligrams for those 18 and younger. A cup of milk or yogurt provides about 300 milligrams, so three servings of dairy per day gets you close. If dairy doesn’t work for you, fortified plant milks, calcium-set tofu, canned sardines or salmon with bones, and fortified orange juice are practical alternatives.
DHA and Omega-3 Fats for Brain Wiring
DHA, a type of omega-3 fat, plays a direct role in your baby’s brain development during the third trimester. It serves as a building block for neuronal maturation and produces compounds that help regulate inflammation in the developing brain, essentially creating a protective environment for new neural connections to form.
The best dietary source is low-mercury seafood. The FDA recommends that pregnant women eat 8 to 12 ounces (two to three servings) per week from lower-mercury options. Salmon, sardines, anchovies, herring, and trout are all good choices. Shrimp, tilapia, and pollock also qualify. Avoid king mackerel, marlin, shark, swordfish, orange roughy, bigeye tuna, and Gulf of Mexico tilefish, all of which carry high mercury levels.
If you don’t eat fish regularly, a prenatal DHA supplement can help fill the gap. Many prenatal vitamins include it, but check the label to confirm.
Choline: The Overlooked Brain Nutrient
Choline rarely gets the same attention as folic acid, but it’s critical in the third trimester. It supports the development of the hippocampus and cerebral cortex, the brain regions responsible for memory and executive function. The recommended intake during pregnancy is 450 milligrams per day.
Most pregnant women don’t come close to that number. Eggs are the single best source, with two large eggs providing roughly 300 milligrams. Beef liver is exceptionally rich in choline, though it’s not to everyone’s taste. Chicken, soybeans, potatoes, and wheat germ also contribute meaningful amounts. If your prenatal vitamin contains choline at all, it likely has only a fraction of the daily target, so food sources matter here.
Carbohydrates and Blood Sugar Balance
The third trimester is when gestational diabetes risk is highest, and even without a diagnosis, blood sugar management becomes more challenging as pregnancy hormones increase insulin resistance. The general guidance is to keep carbohydrates to less than half your total daily calories, and to choose complex carbs over refined ones.
Whole grains, sweet potatoes, oats, brown rice, beans, and starchy vegetables like corn and peas are good carbohydrate sources that digest slowly and release glucose gradually. Pairing carbs with protein or healthy fat at every meal helps prevent the blood sugar spikes and crashes that can leave you feeling drained. Keeping the amount and types of food relatively consistent from day to day also helps your body regulate glucose more predictably.
Fiber for Digestive Comfort
Constipation affects a large percentage of women in the third trimester. Your growing uterus puts physical pressure on your intestines, and the hormones that relax smooth muscle throughout pregnancy slow digestion further. High-fiber foods are the most effective dietary tool to keep things moving: fruits, vegetables, beans, lentils, whole grains, and foods like chia seeds and ground flaxseed.
Increasing fiber gradually is important, because a sudden jump can cause bloating and gas, which are already common complaints at this stage. Pair your fiber intake with plenty of water for the best results.
Managing Heartburn Through Food Choices
Heartburn intensifies for many women in the third trimester as the uterus pushes the stomach upward, making it easier for acid to escape. A few dietary adjustments can make a noticeable difference:
- Eat smaller, more frequent meals rather than three large ones. A full stomach worsens reflux.
- Avoid common triggers like chocolate, peppermint, spicy foods, and caffeinated drinks including coffee, tea, and sodas.
- Stop eating at least two hours before bed. Lying down on a full stomach is one of the most reliable ways to provoke nighttime heartburn.
Some women find that cold milk or yogurt provides temporary relief, though results vary. If heartburn is persistent despite dietary changes, talk with your provider about safe options.
Hydration in the Final Stretch
National guidelines recommend pregnant women drink between 1.9 and 3 liters of water daily (roughly 64 to 100 ounces). This becomes especially important in the second and third trimesters, when your body needs more water to maintain amniotic fluid levels, transport nutrients across the placenta, and support digestion. Research from Penn State found that many pregnant women fall short of these targets.
Plain water is ideal, but milk, herbal teas, and water-rich fruits like watermelon and cucumbers all count toward your daily total. If plain water feels unappealing, adding lemon, cucumber slices, or a splash of juice can help you drink more consistently.
What a Day of Eating Might Look Like
Putting all of this together doesn’t require a complicated meal plan. A practical day might include eggs scrambled with spinach and cheese for breakfast (covering choline, iron, calcium, and protein in one meal), a bean and grain bowl with roasted vegetables for lunch, salmon with sweet potato and broccoli for dinner, and snacks like yogurt with berries, a handful of nuts, or apple slices with peanut butter.
The goal isn’t perfection at every meal. It’s building a general pattern over weeks where iron-rich foods, calcium sources, omega-3 fats, choline, fiber, and protein show up regularly. If your prenatal vitamin is filling some gaps, your plate doesn’t have to carry the full load for every single nutrient every single day. But the nutrients that matter most in the third trimester, particularly calcium, iron, DHA, and choline, benefit from consistent dietary attention because your baby’s demand for them is at its peak.