The third trimester (weeks 28 to 40) is a time of incredible growth and preparation, for both you and your baby. By now, your little one is gaining weight rapidly, building fat stores, and finishing key developmental stages like lung maturation. And your body is working harder than ever to support them.
That makes good nutrition especially important. But “eating well” doesn’t mean perfection or restriction, it means choosing foods that help you stay energized, nourished, and ready for birth. Here’s what to focus on in the final stretch:
What Does Baby Need in the Third Trimester?
During this stage, your baby is:
- Growing rapidly in weight and size
- Building up calcium and iron stores
- Developing brain and lung function
- Strengthening bones, muscles and immunity
To support all this, your diet should include:
- Protein for tissue growth and repair
- Iron for healthy red blood cells
- Calcium for bones and teeth
- Omega-3 fats for brain development
- Fibre to combat constipation
Should I Be Eating More?
You don’t need to “eat for two,” but you may need around 200 extra calories a day in the third trimester - about the amount in a banana with peanut butter or a small bowl of yogurt with fruit.
This extra energy supports your baby’s final growth push, but it’s more about quality than quantity.
What to Include in a Third Trimester Diet
1. Lean Protein
Include a source of protein with every meal to support growth and repair.
- Chicken, turkey, eggs, beans, tofu, yogurt, and lentils
2. Iron-Rich Foods
Iron needs increase in late pregnancy to support your growing blood supply.
- Red meat, leafy greens, dried fruit, fortified cereals, and legumes
- Pair with vitamin C (like citrus fruit or peppers) to boost absorption
3. Whole Grains
Support energy levels and gut health.
- Brown rice, oats, quinoa, wholemeal bread, and pasta
4. Healthy Fats
Crucial for your baby’s brain development.
- Avocados, nuts, seeds, olive oil, and oily fish (like salmon or sardines)
5. Calcium and Vitamin D
For strong bones and teeth.
- Milk, cheese, yogurt, leafy greens, and fortified plant milks
- Continue taking 10 micrograms of vitamin D daily (as recommended by the NHS)
6. Fluids
Aim for 6–8 glasses of water a day. Dehydration can contribute to Braxton Hicks contractions, headaches, and constipation.
Common Challenges (and How to Manage Them)
Heartburn
As your uterus presses on your stomach, heartburn can become more frequent.
- Eat smaller, more frequent meals
- Avoid spicy or greasy foods
- Don’t lie down right after eating
- Sip water rather than drinking large amounts at once
Constipation
Hormonal changes and reduced movement can slow digestion.
- Eat more fibre (fruit, veg, whole grains, lentils)
- Drink plenty of water
- Keep active with gentle walks or stretches
Reduced Appetite
Late pregnancy can leave you feeling full quickly. Try:
- Light, nutrient-dense snacks
- Eating slowly
- Soups or smoothies if solids feel uncomfortable
Foods to Avoid in the Third Trimester
The same food safety rules apply throughout pregnancy:
- No raw or undercooked meat, eggs or fish
- No liver or supplements with vitamin A
- No unpasteurized dairy
- Avoid soft cheeses with mould (e.g., Brie, unless cooked)
- Limit caffeine to 200mg per day (about two mugs of instant coffee)
- Avoid alcohol completely
Midwife’s Top Tips
- Eat small meals more often to manage fullness and heartburn
- Take your vitamin D supplement daily to support you and baby
- Stay hydrated to ease constipation and support amniotic fluid
- Keep healthy snacks nearby for energy dips
- Listen to your body: if you're hungry, eat; if you're full, pause
In the third trimester, nutrition is all about supporting your baby’s final growth phase while keeping yourself strong and well. Focus on variety, hydration, and balance - and don’t worry about eating perfectly every day.
By giving your body what it needs, you’re helping prepare for a smoother birth and recovery. And as always, if you have specific concerns about food, supplements, or weight gain, your midwife is just a conversation away.
