Growing a baby takes a lot of raw material. Your body needs more of almost everything — more protein, more iron, more calcium, more calories in the second and third trimesters — but “eating for two” doesn’t mean doubling your plate. It means making the calories you do eat count.

Here’s what actually matters, broken down by what your body needs and when it needs it most.

The nutrients that do the heavy lifting

Folate (or folic acid)
This is the one nutrient every pregnancy guideline leads with, because it’s tied directly to your baby’s neural tube development — the structure that becomes the brain and spinal cord. That development happens in the first few weeks of pregnancy, often before you know you’re pregnant, which is why folate matters so much before conception too. Leafy greens, lentils, beans, citrus fruit, and fortified cereals are all good natural sources, alongside a prenatal vitamin.

Iron
Your blood volume increases by up to 50% during pregnancy, and all that extra blood needs iron to carry oxygen. Low iron is one of the most common pregnancy deficiencies and can leave you exhausted well beyond normal pregnancy fatigue. Red meat, poultry, beans, and fortified grains help, and pairing iron-rich foods with vitamin C (think spinach salad with orange segments) improves how much your body absorbs.

Calcium and vitamin D
Your baby’s skeleton is being built from your calcium stores, so if your intake is low, your body will pull it from your own bones. Dairy is the obvious source, but fortified plant milks, tofu, and leafy greens work too. Vitamin D helps your body actually use that calcium — sunlight helps, but fortified foods and a prenatal vitamin are the more reliable source.

DHA (an omega-3 fatty acid)
DHA supports your baby’s brain and eye development, particularly in the third trimester, when brain growth accelerates. Low-mercury fish like salmon and sardines are the richest natural sources; if fish isn’t your thing, algae-based supplements are a solid alternative.

Protein
Protein needs increase steadily throughout pregnancy to support your baby’s growth and your own expanding blood supply and tissue. Eggs, poultry, fish, beans, and dairy are all easy ways to build it into meals without much extra effort.

What changes by trimester

First trimester: Calorie needs barely change here — the priority is nutrient quality, not quantity, especially folate. This is also when nausea tends to be worst, so small, frequent, bland meals (crackers, toast, ginger tea) are often more realistic than “balanced” ones. Do what you can keep down; you can rebalance later.

Second trimester: Appetite usually returns, and calorie needs rise modestly (roughly an extra 340 calories a day is the commonly cited figure). This is a good window to focus on iron, calcium, and protein, since baby’s growth is accelerating.

Third trimester: Calorie needs rise a bit further, and DHA becomes especially important as your baby’s brain develops rapidly. Smaller, more frequent meals can also help as there’s simply less room for your stomach to work with.

Foods to be cautious with

A few categories are worth limiting or avoiding due to infection or contamination risk:

• Raw or undercooked meat, eggs, and unpasteurized dairy (listeria and salmonella risk)
• High-mercury fish like swordfish, king mackerel, and shark
• Deli meats and smoked seafood, unless heated until steaming
• Alcohol, which has no established safe amount during pregnancy
• Excess caffeine — most guidelines suggest staying under about 200mg a day, roughly one 12oz coffee

Hydration matters more than people expect

Blood volume, amniotic fluid, and increased circulation all draw on your water intake. Dehydration in pregnancy can contribute to headaches, constipation, and in some cases contractions. Aiming for consistent water intake throughout the day, rather than catching up all at once, tends to work best.

A simple way to think about it

You don’t need a perfect diet — you need a consistent one. A prenatal vitamin covers the gaps; your meals should aim to include a protein source, a fruit or vegetable, and a whole grain most of the time. If nausea, appetite changes, or specific cravings and aversions are making that hard, that’s completely normal, and worth mentioning at your next prenatal visit rather than something to push through alone.

This article is for general educational purposes and isn’t a substitute for personalized medical advice. Always check with your OB-GYN or midwife about your specific nutritional needs, especially if you have dietary restrictions, gestational diabetes, or other pregnancy complications.