How to Eat in the Third Trimester: A Week-by-Week Nutrition Guide

Some days you’re starving an hour after breakfast. Other days, three bites in and you’re already done, even though you know you barely ate. Both are completely normal in the third trimester, and neither means you’re doing anything wrong — your baby is putting on most of their birth weight right now, and your body is simply asking for more fuel to make that happen.

If you only take one thing from this: eat smaller meals more often, lean into protein, iron, calcium, and DHA, get ahead of heartburn before it starts, and don’t cut back on water even when the bathroom trips feel nonstop. Now let’s actually talk through what that looks like on a normal, messy, real-life day.

Why Your Appetite Feels So Different Right Now

Your uterus has taken up so much space by this point that your stomach barely has room to expand. That’s usually why a plate that used to feel completely normal suddenly feels like way too much — even though, an hour later, you’re hunting through the pantry again. Meanwhile, your baby’s brain, bones, and fat stores are developing faster than at any other point in the pregnancy, so the demand for nutrients hasn’t eased up. It’s actually picked up.

So if you’re hungrier but can’t eat as much in one sitting, that’s not a contradiction — it’s your body nudging you toward more, smaller meals instead of three big ones. Most women need roughly 450 extra calories a day in the third trimester, according to CDC and ACOG guidance. In real terms, that’s about an extra snack and a slightly bigger lunch, not a whole second dinner.

What to Actually Put on Your Plate

Protein matters more now than it did earlier on, since it’s doing a lot of the heavy lifting for your baby’s tissue and your own expanding blood supply. Eggs, Greek yogurt, lentils, chicken, tofu, and lower-mercury fish are all easy places to start — nothing fancy needed. Pair protein with a complex carb, like eggs with oatmeal or rice with beans, and you’ll likely notice your energy holds steadier instead of dipping and spiking through the day.

Iron needs climb here too, because your blood volume keeps expanding right up until delivery. Spinach, lean red meat, and fortified cereals help, and a bit of vitamin C alongside them — a squeeze of lemon, some bell pepper — helps your body actually absorb that iron instead of letting it pass through unused. Most providers also recommend sticking with an iron-containing prenatal vitamin at this stage, honestly, because hitting these numbers through food alone is genuinely hard.

Calcium and DHA deserve some attention too. Your baby’s skeleton is hardening fast, and it’s pulling calcium from somewhere — ideally your diet, not your bones. Dairy, fortified plant milks, and leafy greens help there. DHA, the omega-3 found in fatty fish like salmon and sardines, is closely tied to your baby’s brain and eye development, which is part of why it keeps coming up as something worth prioritizing in these final weeks.

Making the Uncomfortable Parts a Little Easier

Heartburn tends to show up, or get worse, right around now — mostly because there’s just less room for your stomach to do its job. Smaller meals help, and so does staying upright for a couple of hours after eating instead of lying straight down. If you’ve noticed spicy, greasy, or very acidic foods setting it off, that’s a pretty common pattern, and it’s worth backing away from those for a while.

Swelling catches a lot of people off guard too, and the instinct is often to drink less water to fight it. That usually backfires. Staying genuinely hydrated actually helps your body manage fluid balance better, so keep the water going steadily through the day rather than in a few big gulps, and go a little easier on heavily salted, processed foods.

Constipation shows up a lot late in pregnancy as well, partly from the extra iron and partly because digestion just slows down. Fiber from fruit, vegetables, and whole grains, along with regular movement and steady hydration, tends to help more than any single fix.

A Few Things Worth Rethinking

Skipping meals to “save room” for dinner usually backfires — it tends to send your blood sugar on a rollercoaster and leave you ravenous later, which rarely ends with a balanced meal. Treating your prenatal vitamin like a stand-in for food is another easy trap to fall into; it’s there to fill gaps, not replace actual eating. And if you’ve been cutting fat out of fear of extra weight gain, it might be worth easing up on that — your baby needs healthy fats, like the kind in avocado, olive oil, and fatty fish, for brain development right now more than at almost any other point in pregnancy.

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