Thyroid Disorders in Pregnancy

Normal thyroid function is essential for fertility, a healthy pregnancy, and fetal brain development. Thyroid disorders should be identified early and managed throughout pregnancy.

Women at Higher Risk

Risk Group	Recommendation
Previous thyroid disease or surgery	Check TSH before or early in pregnancy
Positive thyroid antibodies	Early thyroid function testing
Type 1 diabetes/autoimmune disease	Screen early
History of miscarriage or infertility	Consider thyroid assessment
Family history of thyroid disease	Assess if clinically indicated

Common Pregnancy-Related Thyroid Disorders

Condition	Symptoms	Treatment	Monitoring
Hypothyroidism	Fatigue, constipation	Levothyroxine	TSH about every 4 weeks until stable
Graves’ hyperthyroidism	Palpitations, tremor	Antithyroid medicine	Regular TFTs
Gestational transient thyrotoxicosis	Nausea/vomiting	Usually supportive	Clinical review
Postpartum thyroiditis	Hyper then hypo symptoms	Usually supportive ± levothyroxine	6–12 months follow-up

Medicines in Pregnancy

Medicine	Use	Key Advice
Levothyroxine	Hypothyroidism	Take on an empty stomach; separate iron/calcium by at least 4 hours.
Propylthiouracil (PTU)	Preferred in the 1st trimester for Graves’ disease when antithyroid therapy is required	Use the lowest effective dose.
Methimazole/Carbimazole	Usually preferred after the 1st trimester if ongoing treatment is needed	Monitor thyroid function regularly.

Figure (Placeholder): Pregnancy Thyroid Care Pathway

Pregnancy confirmed → Early TSH/FT4 (if indicated) → Diagnosis → Appropriate treatment → Regular monitoring during pregnancy → Postpartum reassessment

Frequently Asked Questions

Question	Answer
Can thyroid disease affect my baby?	Untreated thyroid disease can increase maternal and fetal risks, but appropriate treatment greatly improves outcomes.
Should I continue levothyroxine during pregnancy?	Yes. Do not stop it without medical advice.
Can I breastfeed while taking thyroid medicine?	Levothyroxine is compatible with breastfeeding. Antithyroid medicines can often be used in appropriate doses under medical supervision.
How often should thyroid tests be checked?	Your doctor will individualize testing; many women with treated hypothyroidism require frequent checks early in pregnancy.

Key Messages

• Plan pregnancy with well-controlled thyroid function.
• Do not stop thyroid medicines without medical advice.
• Attend scheduled thyroid blood tests.
• Regular obstetric and endocrine follow-up improves maternal and fetal outcomes.

References

• American Thyroid Association. Guidelines for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum.
• Endocrine Society Clinical Practice Guideline on Thyroid Disease in Pregnancy.
• European Thyroid Association Guidelines.
• American Diabetes Association/ACOG recommendations where relevant for pregnancy care.