The short explanation
It is generally recommended to have an overactive thyroid well controlled before trying, and to plan the pregnancy with your doctor. Untreated or poorly controlled hyperthyroidism can make it harder to conceive and is linked with higher risks in pregnancy, including miscarriage. Some medicines used for an overactive thyroid are preferred over others around conception and early pregnancy, so your doctor may want to review your treatment before you try. Do not stop or change any medicine on your own.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- How long to wait depends on how stable your thyroid levels are, the cause (such as Graves' disease), and whether you have had or are considering radioactive iodine or surgery, which have their own waiting advice.
- Your doctor will usually want thyroid tests repeated before and during pregnancy, because needs change.
- Tell your doctor as soon as you have a positive test, so treatment can be reviewed early.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This answer cannot tell whether your thyroid is controlled enough to try, or what treatment you should have. Your endocrinologist or physician will decide that.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Are my thyroid levels stable enough to start trying?
- Is my current treatment suitable if I become pregnant?
- How often should my levels be checked before and during pregnancy?
- What should I do as soon as I have a positive test?
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, confusion or vomiting.
Book an appointment soon
- See your doctor within a few days if you have a positive pregnancy test, or symptoms like a racing heart or weight loss returning.
Raise it at a routine appointment
- Book a routine pre-pregnancy visit with your thyroid doctor.
Sources
The evidence this explanation is built on.
- Infertility NHS
- Infertility MedlinePlus (NIH)
- Infertility World Health Organization
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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