What To Eat Third Trimester?

The third trimester is when your baby grows the fastest, and your nutrition needs to shift to match. In these final weeks, your focus should move toward foods rich in iron, calcium, protein, and omega-3 fatty acids, while managing common issues like heartburn and constipation. Prioritizing nutrient-dense whole foods now supports your baby’s brain development and bone growth, and it also prepares your body for the physical demands of labor and recovery.

What Changes in Your Body During the Third Trimester?

Your baby is packing on weight, mostly fat and muscle, which requires a steady supply of calories and nutrients. Your blood volume increases by roughly 40-50% to carry oxygen and nutrients to the placenta. This increases your need for iron and fluids.

Your uterus pushes upward against your stomach, which can cause heartburn and make you feel full quickly. This is why eating smaller, more frequent meals often works better than three large ones. Your digestion also slows down, which can lead to constipation. Fiber and water become just as important as vitamins and minerals.

How Many Extra Calories Do You Actually Need?

During the third trimester, most pregnant women need about 450 extra calories per day compared to their pre-pregnancy needs. That is roughly the equivalent of a peanut butter sandwich on whole-grain bread and a glass of milk. It is not a license to double your portions.

The quality of those calories matters far more than the quantity. A 450-calorie increase should come from nutrient-dense sources, not empty carbohydrates. Think of it as adding a small meal or two large snacks rather than eating for two.

What To Eat Third Trimester: The Core Nutrients

Several nutrients become especially critical in the final weeks of pregnancy. Here is what to prioritize and why.

Protein for Fetal Growth

Protein is the building block for your baby’s tissues and organs. Aim for about 75-100 grams per day, which is slightly higher than earlier in pregnancy. Good sources include lean meat, poultry, fish, eggs, dairy, beans, lentils, and tofu.

If you struggle with meat aversions or nausea, Greek yogurt, cottage cheese, and hard-boiled eggs are easy to tolerate. A smoothie with milk or yogurt and nut butter can also deliver a solid protein punch without much effort.

Iron to Prevent Anemia

Your iron needs jump to about 27 milligrams per day in the third trimester. Iron carries oxygen to your baby and prevents fatigue and anemia in you. Low iron in late pregnancy is linked to higher risks of preterm birth and low birth weight.

Heme iron from animal sources like red meat and poultry is absorbed more easily than plant-based iron. If you rely on plant sources like spinach, lentils, or fortified cereals, pair them with vitamin C — citrus, bell peppers, or tomatoes — to boost absorption. Avoid drinking tea or coffee with iron-rich meals, as tannins block absorption.

Calcium for Bone Development

Your baby’s bones are hardening rapidly in the third trimester, and they need about 1,000 milligrams of calcium per day. If you do not consume enough, your body will leach calcium from your own bones to supply your baby. That can set you up for bone density issues later.

Dairy products are the most concentrated sources. Yogurt, cheese, and milk all work. If you are lactose intolerant or plant-based, fortified plant milks, tofu made with calcium sulfate, and leafy greens like kale and bok choy are good alternatives.

Omega-3 Fatty Acids for Brain Development

DHA, a type of omega-3 fat, accumulates in your baby’s brain and eyes mainly during the third trimester. Research consistently shows that adequate DHA intake supports cognitive development. Fatty fish like salmon, sardines, and trout are the best sources.

Aim for 8-12 ounces of low-mercury fish per week. If you do not eat fish, consider an algae-based DHA supplement, but discuss the dose with your healthcare provider first.

Foods To Eat More Of in the Final Weeks

Some foods deliver outsized nutritional value for the third trimester. Adding these to your routine covers multiple nutrient needs at once.

• Salmon — provides protein, vitamin D, and DHA in one serving.
• Eggs — choline supports your baby’s brain and spinal cord development.
• Greek yogurt — high in calcium and protein, plus probiotics for digestion.
• Beans and lentils — iron, fiber, and plant protein in one package.
• Sweet potatoes — beta-carotene converts to vitamin A, essential for fetal lung development.
• Prunes or prune juice — a reliable, gentle way to combat constipation.
• Fortified whole-grain cereals — iron and B vitamins, especially folic acid.

Foods To Limit or Avoid

Some foods carry real risks in pregnancy, and the third trimester is not the time to relax these rules.

High-mercury fish like shark, swordfish, king mackerel, and tilefish should be avoided entirely. Mercury can damage a developing nervous system. Limit albacore tuna to 6 ounces per week.

Unpasteurized dairy and deli meats carry a risk of listeria, a bacteria that can cross the placenta and cause serious infection. Heat deli meat until steaming before eating. Skip soft cheeses like feta, brie, and queso fresco unless the label says pasteurized.

Alcohol is not safe at any point in pregnancy. No amount has been proven safe, and the third trimester is a critical window for brain development. Caffeine should be limited to about 200 milligrams per day, which is roughly one 12-ounce cup of coffee.

Managing Heartburn and Constipation Through Food

These two issues dominate the third-trimester experience for many women. Your diet can make either better or worse.

Heartburn happens because progesterone relaxes the valve between your stomach and esophagus, and your growing uterus presses on your stomach. Eat smaller meals, avoid lying down for an hour after eating, and skip spicy, greasy, or acidic foods if they trigger symptoms. Ginger tea and oatmeal are gentle options that rarely cause flare-ups.

Constipation is driven by slower gut motility and iron supplements. Increase fiber gradually to 25-30 grams per day, and drink plenty of water. Prunes, pears, and chia seeds are especially effective. If you take an iron supplement, ask your provider whether a stool softener is appropriate.

Hydration: The Overlooked Priority

Dehydration can trigger Braxton Hicks contractions and make fatigue worse. Aim for about 8-10 cups of fluids per day, mostly water. Milk counts toward your calcium goal, and coconut water provides electrolytes.

Watch for signs of dehydration: dark urine, dizziness, dry mouth, or reduced fetal movement. If you notice fewer kicks than usual, drink water and lie on your side. If movement does not pick up, contact your provider immediately.

Sample Third-Trimester Eating Pattern

This is not a prescription — it is a template to show how the nutrients fit into a day.

• Breakfast: Greek yogurt with berries, walnuts, and a sprinkle of chia seeds.
• Morning snack: Apple slices with peanut butter.
• Lunch: Salad with grilled chicken, spinach, bell peppers, and a vinaigrette.
• Afternoon snack: Whole-grain crackers with hummus and carrot sticks.
• Dinner: Baked salmon, quinoa, and roasted sweet potatoes.
• Evening snack: A glass of warm milk and a small handful of almonds.

Adjust portions based on your appetite. Some days you will eat more, some less. That is normal.