Thyroid and Fertility: A Calm TTC Guide for Indian Women

• About 1 in 9 Indian women has a diagnosed thyroid disorder; hypothyroidism (underactive) is far more common than hyperthyroidism (overactive).
• A single TSH blood test (₹200–₹500) catches most cases and is a standard part of any fertility work-up in India.
• Aim for TSH below 2.5 mIU/L before conception and in the first trimester — ideally already in range before you conceive.
• Untreated hypothyroidism can disrupt ovulation and roughly doubles first-trimester miscarriage risk; well-controlled thyroid disease does not.
• Levothyroxine is a once-daily tablet taken on an empty stomach; the dose usually rises 25–30% in early pregnancy, so contact your doctor the week you find out.
• Use iodised salt, but never self-dose iodine or kelp supplements — too much iodine can worsen autoimmune thyroid disease.

The thyroid is a butterfly-shaped gland sitting at the front of your neck, just below the Adam's apple. It makes two main hormones — T3 (triiodothyronine) and T4 (thyroxine) — which together set the speed of your metabolism: how fast you burn calories, how warm you feel, how regular your bowels are, how steadily your heart beats, and how your mood and energy settle through the day.

Thyroid output is controlled by a feedback loop with the pituitary gland in your brain. The pituitary releases TSH (thyroid stimulating hormone): when thyroid levels are low, TSH rises to push the gland harder; when they are high, TSH falls. That is why a TSH blood test is the single most useful screening number — even though it does not measure thyroid hormone itself.

For fertility, what matters most is that thyroid hormones interact closely with the reproductive system. They influence ovulation, cycle length, prolactin levels and the lining of the uterus. When the thyroid drifts out of range, your menstrual cycle often shows it first — sometimes long before the more familiar symptoms appear.

Indian community studies consistently find that roughly 11 percent of adult women have a diagnosed thyroid disorder, with hypothyroidism far more common than hyperthyroidism. Subclinical hypothyroidism — a raised TSH with otherwise normal hormone levels — is even more widespread and easy to miss because the symptoms are so vague.

Several factors push the Indian numbers up: autoimmune thyroid disease (especially Hashimoto's), historical iodine deficiency in certain belts, thyroid changes after pregnancy, and a strong genetic thread that runs in families. Urban women are diagnosed more often partly because they are tested more often, but rural prevalence is significant too. You can read more in our guide to thyroid symptoms in Indian women.

The practical message for anyone trying to conceive is simple: thyroid testing is not idle curiosity — it is a basic part of the fertility work-up in India, and one TSH blood test will catch most of the important cases.

• Symptoms: weight gain that resists effort, feeling cold all the time, persistent fatigue, dry skin, constipation, hair thinning, and heavy or irregular periods.
• Cognitive and mood changes: brain fog, low mood, poor concentration and a general slowing-down that is easy to mistake for stress or ordinary tiredness.
• Commonest cause: Hashimoto's thyroiditis, an autoimmune condition where your own antibodies gradually damage the gland — confirmed by anti-TPO antibodies on a blood test.
• Other causes: iodine deficiency, past thyroid surgery or radioactive iodine, certain medicines such as lithium and amiodarone, and a strong family history.
• Many women have no dramatic symptoms — only a slightly raised TSH on a routine test — which is exactly why it is checked early. For a fuller picture, see hypothyroidism in Indian women.

• Symptoms: unexplained weight loss, a fast or pounding heartbeat (palpitations), heat intolerance, sweating, hand tremor, anxiety, restlessness and trouble sleeping.
• Menstrual changes usually run the other way — lighter, shorter or less frequent periods — and fertility can dip because ovulation becomes irregular.
• Commonest cause: Graves' disease, an autoimmune condition where antibodies overstimulate the thyroid, often with eye changes (puffy, staring eyes) and a visible neck swelling (goitre).
• Other causes: a single overactive nodule or a multinodular goitre making excess hormone, and (less often) early postpartum thyroiditis.
• Hyperthyroidism is less common than hypothyroidism but more dangerous if missed in pregnancy, so a low TSH on screening always needs follow-up — see hyperthyroidism and Graves' disease in pregnancy.

Untreated hypothyroidism disrupts fertility through several routes at once. It often raises prolactin (the milk hormone), which directly suppresses ovulation — a link explored in our guide to high prolactin and difficulty conceiving. It can shorten the luteal phase of the cycle, leaving too little time for a fertilised egg to implant. It also alters cervical mucus and the receptivity of the uterine lining. In women who do conceive, untreated hypothyroidism roughly doubles the risk of first-trimester miscarriage and raises the risk of preterm labour, pre-eclampsia and impaired brain development in the baby.

Untreated hyperthyroidism has its own pattern: faster metabolism, weight loss, lighter periods and often no ovulation at all. In pregnancy, uncontrolled hyperthyroidism raises the risk of miscarriage, preterm birth, low birth weight and a serious emergency called thyroid storm.

The reassuring news is that all of these risks fall sharply once the thyroid is brought into range. Well-controlled thyroid disease — whether hypo or hyper — is fully compatible with normal fertility and a healthy pregnancy. The risk belongs to untreated disease, not to the diagnosis itself. If irregular cycles are part of your picture, how to get pregnant with irregular periods may help.

• Pre-conception (actively trying, or planning within the next few months): TSH below 2.5 mIU/L is the widely accepted target in India, per FOGSI and endocrine society guidance.
• First trimester: TSH below 2.5 mIU/L — ideally already in range before conception so the earliest weeks are protected.
• Second and third trimesters: TSH below 3.0 mIU/L — slightly more relaxed but still tight, reflecting normal pregnancy physiology.
• If your TSH is above target on the first test, don't panic — most women reach target within 6 to 8 weeks of starting or adjusting levothyroxine, and conception is often possible during this time too.
• These targets apply equally whether you are already on levothyroxine or not yet treated. The number on the report is what matters. Trimester-by-trimester detail lives in our pregnancy thyroid TSH targets guide.

• TSH (thyroid stimulating hormone): the single most important screening test, ₹200–₹500 in most Indian labs — abnormal values trigger further testing.
• Free T4 (free thyroxine): measures the active hormone, ₹250–₹500 — useful once TSH is abnormal, to confirm and grade the problem.
• Anti-TPO antibodies: ₹500–₹1500 — confirms autoimmune Hashimoto's, which matters because positive antibodies raise miscarriage risk even when TSH looks borderline.
• Combined TFT (thyroid function test) panel: ₹400–₹1500 — usually bundles TSH, free T3 and free T4, and is the most convenient first test in most fertility work-ups.
• Trusted Indian lab networks include Thyrocare, Metropolis, SRL Diagnostics and Dr Lal PathLabs, with home collection widely available in major cities.
• Repeat testing: once on treatment, TSH is rechecked every 6 to 8 weeks until stable, then every trimester in pregnancy and yearly thereafter.

For hypothyroidism, treatment is a daily tablet of levothyroxine — sold in India as Eltroxin, Thyronorm and several generics, at around ₹30–₹200 a month. Take it on an empty stomach, 30 to 60 minutes before food or tea, because food (especially calcium, iron and soy) blocks absorption. Most women take it first thing in the morning with plain water; some prefer bedtime, at least three hours after dinner.

Doses are adjusted by repeat TSH testing every 6 to 8 weeks until target is reached, then less often. Crucially, levothyroxine should be continued through pregnancy — and the dose almost always rises by 25 to 30 percent in early pregnancy, often before your first antenatal visit. If you become pregnant while on levothyroxine, contact your doctor that same week rather than waiting for the next routine check.

For hyperthyroidism, treatment is more nuanced. The main oral medicines are methimazole or carbimazole (Neomercazole) and propylthiouracil (PTU). In pregnancy, PTU is preferred in the first trimester, with a switch to methimazole later. Radioactive iodine is strictly avoided during pregnancy and for several months before trying to conceive. Surgery (thyroidectomy) is reserved for specific situations. All hyperthyroidism in pregnancy needs joint care with an endocrinologist. If your work-up turns up no clear cause for delayed conception despite normal thyroid results, our unexplained infertility guide explains the next steps.

Iodine is the raw material the thyroid uses to make T3 and T4, so adequate intake matters — especially in pregnancy. India has run a national salt iodisation programme since 1992, and iodised salt is now mandatory for human consumption. Check the salt packet label and use iodised salt for everyday cooking.

Daily iodine needs are about 150 micrograms for adults and 250 micrograms in pregnancy and breastfeeding — an extra 100 micrograms, which a normal Indian diet with iodised salt usually meets. Some prenatal vitamins also include iodine, so check the label and avoid doubling up. Our deeper dive on iodine deficiency in Indian pregnancy covers the goitre-belt geography.

Crucially, more is not better. Excess iodine — from large doses of seaweed, kelp tablets or unsupervised supplements — can itself trigger thyroid dysfunction and worsen autoimmune thyroid disease. Iodine supplements should only be taken on a doctor's specific advice, never as a do-it-yourself fertility hack.

Postpartum thyroiditis is a thyroid inflammation that appears in the first year after delivery, affecting roughly 5 to 10 percent of Indian women. The classic pattern is a hyperthyroid phase between 2 and 6 months (anxious, sleepless, palpitations, weight loss — easy to mistake for new-parent stress) followed by a hypothyroid phase between 6 and 12 months (fatigue, weight gain, low mood — easy to mistake for postpartum depression).

Many women — and many doctors — miss this pattern entirely because the symptoms look like ordinary postpartum life. A simple TSH test at the 6-week postnatal visit, and again at 6 months, catches most cases. If you have a history of thyroid disease, autoimmune disease or a previous postpartum thyroiditis, screening matters even more. Our dedicated guide to postpartum thyroiditis in Indian women goes deeper.

Postpartum thyroiditis often resolves on its own, but a significant number of women need temporary or permanent levothyroxine — and those who recover fully still carry a higher lifetime risk of hypothyroidism. If you are planning your next pregnancy soon, a pre-conception TSH is wise. If you have had a loss and a history of thyroid disease, miscarriage types and recovery in India is a gentle next read.

• Before you start trying: ask for a TSH test as part of your pre-conception check, especially with any family history, irregular cycles or autoimmune disease.
• The week you confirm a pregnancy on levothyroxine — your dose almost always needs to go up, so don't wait for the routine antenatal visit.
• Heavy, irregular or absent periods alongside fatigue, weight change or hair loss — these warrant a TSH and a full check, especially alongside irregular periods and how to conceive with them.
• A new neck swelling (goitre), a lump, difficulty swallowing or a hoarse voice — always have these examined.
• Palpitations, hand tremor, heat intolerance or unexplained weight loss after delivery — possible hyperthyroid phase of postpartum thyroiditis.
• Recurrent pregnancy loss — ask specifically for TSH and anti-TPO antibodies as part of a recurrent miscarriage work-up.

• Myth: "Thyroid means I cannot get pregnant." Fact: Well-controlled thyroid disease is fully compatible with normal fertility and a healthy pregnancy — the risk belongs to untreated disease, not the diagnosis.
• Myth: "Levothyroxine will help me lose weight." Fact: It treats the cause of weight gain in true hypothyroidism but is not a weight-loss drug, and is dangerous if taken without thyroid disease.
• Myth: "Once my TSH is normal I can stop my thyroid medicine." Fact: For most causes (especially Hashimoto's) the gland does not recover, so stopping means TSH rises again within weeks.
• Myth: "Eating more iodine will fix my thyroid." Fact: Iodine deficiency and Hashimoto's are different problems; extra iodine can actually worsen autoimmune thyroid disease.
• Myth: "I should wait until after pregnancy to start treatment." Fact: Untreated hypothyroidism in early pregnancy raises miscarriage, preterm birth and developmental risks — treatment is far safer than waiting.
• Government note: under the PMSMA (Pradhan Mantri Surakshit Matritva Abhiyan) scheme, a free thyroid function test is offered in the first trimester at government antenatal centres across India — a good entry point if you are uninsured.

• American Thyroid Association — Guidelines for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum
• World Health Organization — Iodine deficiency
• Indian Thyroid Society / ICMR — Thyroid disorders in India and pregnancy
• Ministry of Health and Family Welfare, Government of India — Pradhan Mantri Surakshit Matritva Abhiyan (PMSMA)
• NHS — Underactive thyroid (hypothyroidism)