Your thyroid is a small gland in your neck, but its hormones affect your periods, ovulation, the early weeks of pregnancy and your baby’s brain development. Thyroid problems are common among Indian women and often go unnoticed. The good news is that they are easy to test and simple to treat. This guide explains how thyroid health affects fertility, IVF and pregnancy. It is part of the care we provide at Lifeline IVF in Ahmedabad and our maternity hospital.
How Does the Thyroid Affect Fertility?
Thyroid hormones help control your metabolism and work closely with your reproductive hormones. When levels are too low or too high, they can:
- Make periods irregular, heavy or absent
- Stop or delay ovulation
- Raise prolactin, which can further disturb ovulation
- Increase the risk of miscarriage and preterm birth
- Affect the baby’s brain development if untreated in early pregnancy
Hypothyroidism vs Hyperthyroidism
| Hypothyroidism (underactive) | Hyperthyroidism (overactive) | |
| How common | More common in women planning pregnancy | Less common |
| Common symptoms | Tiredness, weight gain, feeling cold, constipation, dry skin, hair fall, heavy periods | Weight loss, fast heartbeat, anxiety, sweating, light or absent periods |
| Usual treatment | Daily levothyroxine tablet | Medicines; specialist care |
Many women have no symptoms at all, especially with mild (subclinical) hypothyroidism, which is why a blood test matters.
Which Thyroid Tests Do You Need?
- TSH (thyroid-stimulating hormone) — the main screening test
- Free T4 — if TSH is abnormal
- Thyroid antibodies (anti-TPO) — in some women, for example after miscarriage or with a family history
These are usually part of a pre-conception check-up and every fertility work-up. See our guide to female fertility tests.
What TSH Level Is Good for Getting Pregnant?
The American Thyroid Association recommends that women already on thyroid medicine who are planning pregnancy keep their TSH at the lower end of normal and no higher than 2.5 mU/L before conception. For women having IVF or ICSI with mild (subclinical) hypothyroidism, treatment is recommended with a goal TSH below 2.5 mU/L (ATA 2017 guideline summary). Your doctor will interpret your result with your lab’s range and your history.
What Is Subclinical Hypothyroidism?
Subclinical hypothyroidism means your TSH is raised but your free T4 is still normal. It is common, often causes no symptoms and is usually found on routine tests before pregnancy or IVF. Whether it needs treatment depends on your TSH level, thyroid antibodies and whether you are having fertility treatment. A low dose of levothyroxine is often advised for women planning IVF, because it is safe and prevents the thyroid from becoming more underactive once you are pregnant.
Reading Your TSH Report
Your report shows your result next to the lab’s reference range, which is usually wider than the target used before pregnancy. A TSH within the lab’s “normal” range may still be above the level your fertility doctor wants. Always bring your report to your consultation rather than judging it on your own.
Thyroid and IVF
Before IVF, every woman should have a TSH test. If it is above target, treatment is started and the test repeated after 4–6 weeks so the IVF cycle starts with well-controlled levels. Thyroid medicine is safe to take throughout IVF and pregnancy.
Thyroid During Pregnancy
Pregnancy increases the body’s need for thyroid hormone. If you already take levothyroxine:
- Tell your doctor as soon as your pregnancy test is positive — the dose usually needs to go up straight away
- Expect TSH checks about every 4 weeks until mid-pregnancy
- Do not stop or change your tablets on your own
Women with positive thyroid antibodies but normal levels also need regular TSH checks in early pregnancy, because levels can drop. These checks are part of our prenatal care.
Thyroid, PCOS and Miscarriage
Thyroid problems are more common in women with PCOS, and both can cause irregular periods — so both should be checked. Read our PCOS treatment guide. Untreated hypothyroidism is also one of the treatable causes looked for after repeated pregnancy loss; see recurrent miscarriage.
Iodine and Diet
Your thyroid needs iodine to make its hormones, and the need rises in pregnancy — the World Health Organization recommends about 250 micrograms a day for pregnant and breastfeeding women. In India, using iodised salt in cooking is the simplest way to get enough. Do not take kelp or seaweed supplements, which can contain too much iodine. Your prenatal vitamin may also contain iodine; ask your doctor before adding anything extra.
Planning Pregnancy with an Overactive Thyroid
If you have hyperthyroidism or Graves’ disease, plan pregnancy together with your doctor. Thyroid levels should be well controlled before you try, and some medicines are changed before or in early pregnancy. Avoid becoming pregnant soon after radioactive iodine treatment; your doctor will advise how long to wait.
Thyroid After Delivery
Some women develop postpartum thyroiditis in the first year after giving birth. It often starts with a short overactive phase (palpitations, anxiety, weight loss) followed by an underactive phase (tiredness, low mood, weight gain). Because these symptoms are easily mistaken for normal new-mother tiredness, ask for a TSH test if you feel unwell after delivery.
When to See a Doctor
- Irregular or absent periods
- Trying to conceive for 12 months (6 months if over 35) without success
- Symptoms of an under- or overactive thyroid
- A family history of thyroid disease, or type 1 diabetes
- A previous miscarriage, or a positive pregnancy test while on thyroid medicine
How to Take Thyroid Tablets Correctly
- Take levothyroxine on an empty stomach, ideally first thing in the morning with water
- Wait 30–60 minutes before breakfast or tea/coffee
- Keep a 4-hour gap from iron and calcium tablets (often given in pregnancy)
- Take it every day and do not double up if you miss a dose without advice
| Planning a pregnancy or IVF? A simple thyroid check is part of every fertility consultation with Dr. Maulik Shah at Lifeline Women’s Hospital & IVF Centre, Gota. Call +91 98988 66044 or book online. |
Frequently Asked Questions
Can thyroid problems cause infertility?
Yes. Both underactive and overactive thyroid can disturb ovulation and periods. Treatment often restores normal cycles.
What TSH level is ideal before pregnancy?
For women on thyroid medicine, guidelines suggest keeping TSH at the lower end of normal and no higher than 2.5 mU/L before conception.
Can I get pregnant with hypothyroidism?
Yes. With the right dose of levothyroxine and regular checks, most women with hypothyroidism conceive and have healthy pregnancies.
Is thyroid medicine safe in pregnancy?
Yes. Levothyroxine is the same hormone your body makes, and it is safe for you and your baby. The dose usually needs to increase in pregnancy.
Does my husband need a thyroid test?
Thyroid problems can occasionally affect sperm, so men with symptoms may be tested as part of a fertility work-up.
How often should TSH be checked during pregnancy?
For women on treatment or with thyroid antibodies, about every four weeks until mid-pregnancy, then as advised.
Author & Medical Review
Dr. Maulik Shah MBBS, MS (Obstetrics & Gynaecology) — Diploma in Infertility (Germany) | Consultant Gynaec & Infertility Specialist. Medically reviewed by Dr. Maulik Shah.
