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Management of Thyroid Diseases in Pregnancy

Trimester-specific management of thyroid function during pregnancy.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Internal Medicine department. Book Appointment →

What is Management of Thyroid Diseases in Pregnancy?

Thyroid physiology changes significantly during pregnancy: hCG stimulation of TSH receptor, estrogen-related TBG increase, and increased iodine requirements make trimester-specific reference ranges mandatory. The TSH upper limit is accepted as ~4.0 mIU/L in the first trimester.

Hypothyroidism is seen in 2-3% of pregnancies and, if untreated, increases the risk of preeclampsia, miscarriage, preterm birth, and fetal neurocognitive developmental impairment. Levothyroxine doses generally need to be increased by 25-50% during pregnancy.

In hyperthyroidism cases, Graves' disease is the most common cause. Propylthiouracil (PTU) is preferred in the first trimester, while transition to methimazole is recommended in the second-third trimester. Radioactive iodine is absolutely contraindicated in pregnancy.

Symptoms

In hypothyroidism: Excessive fatigue, constipation, weight gain, cold intolerance
In hyperthyroidism: Palpitations, weight loss, hand tremor, heat intolerance
Gestational thyrotoxicosis (due to elevated hCG — accompanied by hyperemesis gravidarum)
Thyroid nodule (may grow during pregnancy)
Postpartum thyroiditis (1-6 months after delivery)

Risk Factors

History of known thyroid disease
Type 1 diabetes or other autoimmune diseases
Thyroid autoantibody positivity (anti-TPO)
Family history of thyroid disease
Thyroid disorder in previous pregnancy
Living in iodine-deficient areas

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Thyroid patients planning pregnancy or becoming pregnant should seek follow-up
  • Endocrinology consultation for newly detected thyroid dysfunction during pregnancy
  • TSH monitoring (every 4 weeks) for dose adjustment in pregnant women on levothyroxine
  • If new thyroid symptoms develop in the postpartum period

Treatment Methods

01
Hypothyroidism: Levothyroxine (pre-pregnancy dose increased 25-50%, target TSH <2.5)
02
Hyperthyroidism: PTU (1st trimester) → Methimazole (2nd-3rd trimester)
03
Gestational thyrotoxicosis: Usually self-limiting, antithyroid drugs not required
04
Thyroid nodule: FNAB can be performed during pregnancy, surgery preferred in 2nd trimester if needed
05
Postpartum thyroiditis: Symptomatic treatment, 20-30% develop permanent hypothyroidism
06
Iodine supplementation (150-250 µg/day — during pregnancy and lactation)

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You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.