The short explanation
Do not stop your thyroid medicine. In early pregnancy the baby relies on the mother's thyroid hormone, and the body's need usually goes up, so stopping can cause problems. Contact your doctor soon, ideally within the next few days, to tell them you are pregnant. They usually check your thyroid levels and often adjust the amount you take early in pregnancy. Thyroid levels are then usually checked regularly through pregnancy, because needs change as the pregnancy progresses, and again after delivery.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- Taking the tablet consistently in the way your doctor advised, and keeping some distance from iron and calcium supplements, helps it work properly; ask your doctor how this applies to you.
- An overactive thyroid in pregnancy is managed differently, and some medicines for it are changed in pregnancy, so tell your doctor which condition you have.
- Bring your recent thyroid reports to your first antenatal visit.
- This applies to other long-term medicines too: do not stop them suddenly without talking to your doctor.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you whether your treatment needs adjusting. Only your doctor, using your current blood test results, can decide that.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Does my thyroid medicine need adjusting now that I am pregnant?
- When should my thyroid levels be checked during pregnancy?
- How should I take my thyroid tablet alongside iron or calcium?
- What happens to my treatment after delivery?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Emergency — call 112 now
- Call 112 or go to the nearest emergency department if you have a very fast heartbeat with fever or confusion, heavy bleeding, or severe belly pain.
Book an appointment soon
- See your doctor within a few days to tell them you are pregnant and check your thyroid levels.
Raise it at a routine appointment
- Have thyroid tests at the intervals your doctor advises throughout pregnancy.
Sources
The evidence this explanation is built on.
- Thyroid disease and pregnancy NIDDK (NIH)
- Prenatal care MedlinePlus (NIH)
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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