Thyroid Care During Pregnancy: What You Need to Know

When you're pregnant, your thyroid, a small butterfly-shaped gland at the base of your neck that controls metabolism and energy use. Also known as thyroid gland, it works harder than ever to support both you and your growing baby. Even small changes in thyroid function can impact fetal brain development, increase the risk of preterm birth, or lead to preeclampsia. Many women don’t realize their thyroid is off until it’s already causing problems—because symptoms like fatigue, weight gain, or mood swings are often written off as normal pregnancy side effects.

That’s why TSH levels, the measure of thyroid-stimulating hormone used to check thyroid function. Also known as thyroid panel, it must be monitored closely during pregnancy. Normal TSH ranges shift by trimester: under 2.5 mIU/L in the first trimester, under 3.0 in the second, and under 3.5 in the third. If you have hypothyroidism, a condition where the thyroid doesn’t make enough hormone. Also known as underactive thyroid, it, you’ll likely need to increase your levothyroxine dose—often by 25% to 50%—as early as the first trimester. Skipping this step can affect your baby’s IQ and motor skills. On the flip side, untreated hyperthyroidism can lead to miscarriage or low birth weight. Both conditions need expert management, not guesswork.

Medication safety matters too. Levothyroxine is safe during pregnancy—no risk to the baby—and should never be stopped. But other thyroid drugs, like radioactive iodine or antithyroid meds in high doses, can be dangerous. Your doctor should check your thyroid every 4 to 6 weeks in the first half of pregnancy, then at least once after 30 weeks. And if you had thyroid issues before pregnancy, don’t wait for symptoms. Get tested as soon as you know you’re pregnant.

What you’ll find in the posts below isn’t just theory. These are real-world guides from people who’ve walked this path—how to read lab results, what to ask your OB, how to spot hidden thyroid problems, and why some women need to switch meds mid-pregnancy. No fluff. No jargon. Just clear, practical advice to help you stay in control when your body is changing faster than ever.