When it happens · 4 min read
Heartburn, constipation, and the third-trimester gut
Nobody warns you that a substantial part of late pregnancy is a digestive event. Here's why it happens and what genuinely helps — plus the two things that masquerade as indigestion and aren't.
Last updated August 9, 2026
Why it all slows down
Progesterone relaxes smooth muscle throughout your body, which is useful for a growing uterus and unhelpful for a digestive tract that relies on muscle tone. The valve at the top of the stomach relaxes, letting acid up. The gut moves food along more slowly, drawing out more water and hardening stool. Then in the third trimester the uterus physically compresses the stomach and bowel. Add iron in prenatal vitamins, which constipates, and the picture is complete.
Heartburn
Smaller, more frequent meals rather than large ones. Stop eating a couple of hours before lying down. Prop the head of the bed up, or sleep more upright with pillows — gravity does real work here. Identify triggers, which are commonly spicy, fatty, acidic, chocolate, and caffeine. Milk sometimes helps briefly.
For medication, ask what's suitable — calcium-based antacids are commonly recommended in pregnancy, and stronger acid-reducing medications are used when needed. This is worth asking about rather than enduring nightly; poor sleep from reflux compounds everything else.
Constipation and hemorrhoids
Fluids first, and more than you think. Fiber from fruit, vegetables, and whole grains, increased gradually so it doesn't just produce gas. Movement, even a short daily walk. Don't ignore the urge. Stool softeners are commonly recommended in pregnancy and are generally considered safe — ask rather than assuming you must go without.
If iron is the culprit, ask about a different formulation or taking it with vitamin C. For hemorrhoids: witch hazel pads, warm baths, not sitting on the toilet for long stretches, and treating the constipation, since straining is what creates them. Bleeding that's more than streaks, or a sudden hard painful lump, warrants a call.
The two that aren't indigestion
Pain in the upper right abdomen or under the ribs — particularly with a severe headache, vision changes, or sudden swelling of the face and hands — can be preeclampsia. People routinely file this under heartburn. Same-day call.
Intense itching without a rash, worst on palms and soles and worse at night, can be cholestasis of pregnancy and needs a bile acid blood test rather than antihistamines.
Common questions
- Does heartburn really mean a hairy baby?
- Amusingly, one small study did find a correlation, probably via the same hormones affecting both. It's a fun fact, not a reason to expect anything in particular.
- Are antacids safe throughout pregnancy?
- Many are commonly used, but they're not all equivalent — some contain ingredients better avoided in pregnancy, and antacids can interfere with iron absorption if taken together. Ask your provider or pharmacist which one and when.
- How much fiber is too much, too fast?
- Jumping straight to a lot of fiber without matching fluids tends to produce bloating and gas rather than relief. Increase gradually and drink more alongside it.
If it's this, not that
Still not sure
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