Thyroid problems are common in women of childbearing age, and pregnancy itself changes how the thyroid gland works. That is why thyroid function testing is now a standard part of early antenatal care in India. If your report has come back with an abnormal TSH or if you already take thyroid medication and have just found out you are pregnant, this article will help you understand what it means and what to do.
Why the thyroid matters in pregnancy
The thyroid gland produces hormones that regulate metabolism, energy, and, crucially, fetal brain development. In the first trimester, the baby depends entirely on the mother's thyroid hormones because its own thyroid gland does not start working until around 12 to 14 weeks. Even after that, the baby continues to rely partly on the mother's supply. Untreated thyroid imbalance during this period can affect the baby's growth and neurological development, and can also increase the risk of pregnancy complications.
Hypothyroidism (underactive thyroid) in pregnancy
This is the more common thyroid issue in pregnancy. TSH levels are higher than the trimester-specific reference range. It can be a pre-existing condition or one detected for the first time during antenatal screening.
- Symptoms overlap with normal pregnancy complaints: fatigue, constipation, weight gain, dry skin. This is why blood tests are necessary rather than relying on symptoms alone.
- Untreated hypothyroidism raises the risk of miscarriage, pre-eclampsia, anaemia, placental problems, and preterm delivery.
- Treatment is straightforward: levothyroxine, the same medication used outside pregnancy, with dose adjustments guided by regular blood tests. Many women who were already on thyroid medication before pregnancy will need a dose increase, sometimes within the first few weeks.
- TSH is typically rechecked every four to six weeks during pregnancy and the dose is adjusted as needed.
Hyperthyroidism (overactive thyroid) in pregnancy
Less common, but needs careful management. The most frequent cause is Graves' disease.
- Symptoms include a rapid or irregular heartbeat, tremor, unexplained weight loss, heat intolerance, and anxiety beyond what is expected.
- Mild hyperthyroidism in early pregnancy can sometimes be due to the normal surge of hCG (the pregnancy hormone) and does not always need treatment.
- More significant hyperthyroidism may require anti-thyroid medication. The choice of drug and dose is carefully decided by your doctor, since some medications cross the placenta.
- Uncontrolled hyperthyroidism increases the risk of miscarriage, preterm birth, low birth weight, and a dangerous blood pressure condition called thyroid storm.
Postpartum thyroiditis
Some women develop thyroid inflammation in the months after delivery, typically between 2 and 6 months postpartum. It can cause a brief phase of hyperthyroidism followed by hypothyroidism, and it is sometimes mistaken for postnatal depression or simply the fatigue of new motherhood. If you are feeling unusually tired, anxious, or low in the months after delivery, mention it to your doctor and ask for a thyroid check.
Key takeaways
- Get your thyroid function tested in early pregnancy, ideally in the first trimester.
- If you are already on thyroid medication, inform your gynaecologist as soon as you know you are pregnant. Do not stop or change the dose on your own.
- Attend all follow-up blood tests so your dose can be adjusted as your pregnancy progresses.
- After delivery, your medication dose may need to be brought back to the pre-pregnancy level.
Pregnancy can be an emotional time, and an abnormal test result adds to the stress. If anxiety or low mood is affecting you, please talk to your doctor. You can also reach the free national Tele-MANAS mental health helpline at any time on 14416 (or 1800-891-4416). If you or someone near you is in immediate danger, call 108 or go to the nearest hospital.
A word from our clinic
I am Dr. Samta Singhania, a gynaecologist and obstetrician with 22 years of experience, practising at Prudent International Health Clinic in Viman Nagar, Pune. This article was reviewed by Dr. Rajiv Kumar, our diabetologist and general physician, who manages thyroid disorders. We coordinate thyroid monitoring as part of your antenatal care so nothing falls through the gaps. We are open all 7 days, 9 AM to 9 PM, with walk-ins welcome. Call or WhatsApp us on +91 70287 22200. For current pricing, call the clinic on +91 70287 22200.
