Pregnancy Diet by Trimester: What to Eat When

Your nutritional needs change in every trimester — not just in calories, but in the specific micronutrients required to build organs, blood, brain, and bone. This guide breaks down what to eat in each trimester with daily targets aligned with the American College of Obstetricians and Gynecologists (ACOG), USDA MyPlate for Moms, and the National Institutes of Health Office of Dietary Supplements.

📌 Key Takeaway: According to March of Dimes data, about 10% of US babies are born preterm (before 37 weeks), making week-by-week monitoring important. This guide gives you evidence-based, practical guidance you can apply today. For a related deep dive, see our guide on pregnancy insomnia by trimester.

Daily Nutritional Targets at a Glance

First Trimester (Weeks 1-13): Foundation

Calorie Needs

No additional calories required. Despite the saying “eating for two,” you do not need extra energy in the first trimester.

Key Nutrients

• Folate (600 mcg) — Critical for neural tube formation, which closes by week 6. Best from a prenatal vitamin plus dark leafy greens, lentils, fortified cereals, and citrus.
• Vitamin B6 (1.9 mg) — Helps with nausea. Bananas, chicken, potatoes.
• Iodine (220 mcg) — Brain development. Iodized salt, dairy, seafood (low-mercury), eggs.
• Choline (450 mg) — Brain and spinal cord. Eggs (1 large = 147 mg), beef, soybeans.

Eating Through Nausea

If morning sickness is severe, focus on getting any nutrition in:

• Small, frequent meals (every 2-3 hours)
• Bland carbs: crackers, toast, plain rice
• Cold foods often tolerated better than hot
• Ginger tea or candies
• Protein with each meal/snack to stabilize blood sugar
• Don’t skip the prenatal vitamin — take it at night with food

Foods to Avoid (All Trimesters)

• Raw or undercooked meat, fish, eggs
• High-mercury fish (shark, swordfish, king mackerel, tilefish, bigeye tuna)
• Unpasteurized dairy and juices
• Deli meats and pâtés (unless heated to steaming)
• More than 200 mg caffeine/day (about 12 oz coffee)
• Alcohol (zero)
• Raw sprouts

Second Trimester (Weeks 14-27): Build

Calorie Needs

+340 calories/day — about a peanut butter sandwich with a glass of milk, or a Greek yogurt parfait with granola and fruit.

Key Nutrients

• Protein (71 g) — Rapid fetal tissue growth. Aim for 25g at each main meal: 4 oz chicken (28g), Greek yogurt (15-20g), 2 eggs (12g), 1 cup lentils (18g).
• Calcium (1,000 mg) — Bone formation begins in earnest. 3 servings of dairy or fortified alternatives daily.
• Iron (27 mg) — Blood volume increasing. Detail in our iron-rich foods guide.
• Omega-3 DHA (200-300 mg) — Brain and eye development. Salmon (low-mercury), sardines, algae oil supplement. See DHA & Omega-3 in Pregnancy.

Sample Second Trimester Day

Third Trimester (Weeks 28-40): Polish

Calorie Needs

+450 calories/day — about a turkey sandwich plus an apple, or a salmon and quinoa bowl.

Key Nutrients

• Calcium (1,000 mg) — Major skeletal mineralization happens now.
• Iron (27 mg) — Baby builds iron stores for first 6 months of life.
• DHA (200-300 mg) — Major brain growth phase.
• Vitamin K (90 mcg) — Newborn clotting. Leafy greens.
• Magnesium (350-360 mg) — Helps with leg cramps. Pumpkin seeds, almonds, dark chocolate.
• Fiber (28g) — Combats constipation common in third trimester. Whole grains, legumes, fruits.

Strategies for Third Trimester Discomforts

• Heartburn: smaller meals, avoid late eating, sit upright after meals
• Constipation: 8-10 glasses of water/day, prunes, ground flax in oatmeal
• Swelling: continue salt in moderation (don’t restrict), elevate feet, stay hydrated
• Fatigue: pair iron-rich foods with vitamin C; eat every 3 hours

Hydration Targets

• First trimester: 8-10 cups (64-80 oz) water/day
• Second trimester: 10 cups
• Third trimester: 10-12 cups
• Add electrolytes if exercising or in hot climate

Weight Gain Guidelines (IOM/ACOG 2009, still current)

Vegetarian and Vegan Diets in Pregnancy

Plant-based pregnancies are absolutely safe with planning:

• Protein: tofu, tempeh, lentils, beans, quinoa
• Iron: pair plant iron with vitamin C (oranges with spinach)
• B12: fortified foods or supplement (essential — animal-only naturally)
• Omega-3 DHA: algae-based supplement
• Calcium: fortified plant milks, tahini, kale
• Vitamin D: supplement; sunlight insufficient for most

Frequently Asked Questions

Do I need to “eat for two” in pregnancy?

No. You need 0 extra calories in the first trimester, +340 in the second, and +450 in the third — about one extra small meal or snack, not two full meals.

Is decaf coffee safe during pregnancy?

Yes, in moderation. Stay under 200 mg total caffeine/day. Decaf still contains 2-15 mg per cup.

Can I eat sushi during pregnancy?

Cooked sushi (cooked shrimp, eel, or vegetable rolls) is fine. Raw fish is not recommended due to listeria and parasite risk. Smoked fish from refrigerated cases should also be avoided unless heated.

How much fish is safe per week?

2-3 servings (8-12 oz) of low-mercury fish per week — salmon, sardines, light tuna, trout, cod, tilapia. Avoid shark, swordfish, king mackerel, tilefish, bigeye tuna.

Should I take a prenatal vitamin if I eat well?

Yes. Even a perfect diet rarely meets folate, iron, and DHA needs of pregnancy. The ACOG recommends a daily prenatal for all pregnant people. See our best prenatal vitamins.

💡 Related Resources: After baby arrives, visit our sister site baby.chparenting.com for newborn care, sleep training, feeding guides, and developmental milestones.

References

1. ACOG — Nutrition During Pregnancy: https://www.acog.org/womens-health/faqs/nutrition-during-pregnancy
2. USDA MyPlate for Moms: https://www.myplate.gov/life-stages/pregnancy-and-breastfeeding
3. NIH Office of Dietary Supplements — Folate: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
4. CDC — Folic Acid Recommendations: https://www.cdc.gov/folic-acid/about/
5. FDA — Advice About Eating Fish: https://www.fda.gov/food/consumers/advice-about-eating-fish

Medical Disclaimer

This article provides general nutrition information and is not a substitute for personalized medical advice. Discuss your specific dietary needs and any supplementation with your obstetrician, midwife, or registered dietitian.

Written by

Vega Lin

Founder & Editor — Mother of 2 (Taiwan)

Vega writes Pregnancy Guide from the intersection of evidence-based research (ACOG, CDC, WHO) and her own experience as a mother of two. Completing her Master's in Digital Innovation at Tunghai University. Read more →

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