How common is tiredness in pregnancy in underactive thyroid in pregnancy?

Low thyroid hormone activity can slow body processes and may leave you unusually tired, slowed down, or unable to concentrate.

Fatigue is also a normal pregnancy complaint, so tiredness alone cannot identify an underactive thyroid. Other possible features include feeling unusually cold, constipation, dry skin, low mood, or difficulty concentrating. Blood tests that measure thyroid function help a clinician decide whether thyroid treatment or another explanation is relevant.

Tell your maternity or primary-care team if tiredness is persistent, worsening, or accompanied by other thyroid symptoms. If you already take thyroid replacement, keep taking it as prescribed and ask when your levels should be reviewed. Do not change the dose or add iodine products without clinical guidance.

Arrange prompt advice for severe fatigue with fainting, breathlessness at rest, chest pain, confusion, or a heartbeat that remains very fast. Contact your team sooner if you have known thyroid disease and cannot keep your medicine down or have missed several doses.

Ask whether thyroid-function testing is needed, how pregnancy affects your treatment plan, when repeat testing is appropriate, and what to do after a missed dose or vomiting.