What causes morning sickness?
Last updated September 3, 2026.
Morning sickness is driven by the hormone surge of early pregnancy - chiefly hCG, which peaks exactly when nausea does, plus estrogen and digestion-slowing progesterone - amplified by a newly razor-sharp sense of smell. The empty-stomach effect is real, which is why mornings and skipped meals hit hardest, and the name is a lie: it strikes at any hour. Ordinary morning sickness does not raise risk to the baby. The exception is hyperemesis gravidarum: relentless vomiting, nothing staying down, dehydration, weight loss - that needs medical treatment. Risk runs higher with twins, previous severe episodes, or family history. Pymander is a free AI doctor, 24/7 by text, and can help you tell normal from severe.
What to do
- Eat small and often: an empty stomach is the biggest daily trigger.
- Keep dry carbs by the bed: crackers before sitting up is a classic for a reason.
- Track your fluids: inability to keep even sips down is the hyperemesis red line.
- Get help if vomiting is relentless: dehydration and weight loss need treatment, not endurance.
Related questions
- How long does morning sickness last?
- What helps nausea fast?
- Can dehydration cause dizziness?
- How to know if your period is normal?