Thyroid and fertility
The thyroid gland controls the body's metabolism, and it also affects periods, ovulation and pregnancy. Thyroid problems are common in Indian women and are simple to test for and usually simple to treat. At EVE Women and Fertility Clinic in Gunjur, Bangalore, Dr. Swati Shree checks thyroid function as part of fertility and miscarriage evaluations, and helps you keep it in the right range before and during pregnancy.
At a glance
- Test
TSH, a simple blood test, with free T4 when needed; thyroid antibodies in selected women
- Target when planning pregnancy
many guidelines aim for a TSH below about 2.5 mIU/L. Your doctor sets your own target.
- Treatment
daily thyroid hormone tablets for an underactive thyroid, taken on an empty stomach
How the thyroid affects fertility
Thyroid hormone influences the signals that control ovulation. When it is too low, periods can become irregular or heavy, ovulation can stop, and prolactin can rise. Even mild hypothyroidism, with a raised TSH and normal T4, can matter when trying to conceive. Untreated thyroid disease raises the risks of miscarriage, preterm birth, and effects on the baby's development. These are largely preventable with treatment.
Who should be tested
Dr. Swati advises thyroid testing for women who:
- Are trying to conceive and have not yet, or are starting fertility treatment
- Have irregular periods, PCOS or heavy periods
- Have had a miscarriage, especially more than one
- Have a family history of thyroid disease, or other autoimmune disease such as type 1 diabetes
- Have symptoms such as tiredness, weight change, hair loss, cold or heat intolerance, or a swelling in the neck
Thyroid antibodies
Some women have antibodies against the thyroid (TPO antibodies) even with normal TSH. They are linked with a higher risk of miscarriage in some studies. The benefit of treating antibodies alone is not clearly proven, so Dr. Swati checks thyroid function more often and treats if TSH rises.
What happens at EVE
A blood test
for TSH, with free T4 and antibodies as indicated.
Treatment if needed
For an underactive thyroid, thyroid hormone tablets. For an overactive thyroid, medicine and a plan with a physician or endocrinologist.
Retesting
after about 6 to 8 weeks, to adjust the dose.
Planning pregnancy
Aim for a target TSH before treatment such as IUI or IVF, and recheck in early pregnancy.
In pregnancy
The dose is checked early and often adjusted, and testing is repeated through the pregnancy.
Taking thyroid medicine well
- Take it on an empty stomach, with water, about 30 to 60 minutes before breakfast, at the same time daily
- Separate it from iron, calcium and some other supplements by at least 4 hours
- Do not stop or change the dose yourself
- If you become pregnant, contact us at once about the dose
When to see a doctor
- Irregular periods, difficulty conceiving or a miscarriage, with no thyroid check yet
- Known thyroid disease and planning pregnancy
- A positive pregnancy test while on thyroid medicine
FAQs
Can hypothyroidism cause infertility?
Yes. An underactive thyroid can cause irregular ovulation, heavy or irregular periods, and a higher risk of miscarriage. Most women conceive once thyroid levels are corrected with medicine. It is one of the simplest causes of infertility to test for and treat.
What TSH level is right when trying to conceive?
Many guidelines aim for a TSH below about 2.5 mIU/L when planning pregnancy, though targets vary slightly. Dr. Swati sets a target for you, based on your tests and history, and adjusts your dose to reach it.
Do I need to change my thyroid dose in pregnancy?
Often, yes. Pregnancy raises the need for thyroid hormone, and many women need a higher dose, often by about 25 to 30 percent. Contact your doctor as soon as you have a positive test, and do not adjust the dose on your own.
Does thyroid medicine harm the baby?
No. Thyroid hormone replacement is safe in pregnancy, and untreated hypothyroidism is far more harmful. Overactive thyroid needs particular care in medicine choice. Dr. Swati explains your plan and coordinates with an endocrinologist when needed.
Should I get thyroid antibodies tested?
They may be useful if you have had miscarriages, or if TSH is borderline. Having antibodies increases the chance of thyroid problems later, so monitoring is advised. Treating antibodies alone is not clearly proven to help. Dr. Swati decides whether testing is useful for you.
Can thyroid problems cause irregular periods?
Yes. Both underactive and overactive thyroid can change cycle length and flow. A thyroid test is part of the first check for irregular periods. See the Menstrual disorders and PCOS pages.
Sources
- American Thyroid Association guidelines for the diagnosis and management of thyroid disease during pregnancy and the postpartum (2017)
- Endocrine Society guideline: Management of thyroid dysfunction during pregnancy and postpartum
- ESHRE Guideline: Recurrent pregnancy loss (2022)
- Indian Thyroid Society guidance
