When you're pregnant and taking thyroid medication, a hormone replacement therapy used to treat underactive thyroid, commonly prescribed as levothyroxine. Also known as levothyroxine, it's not just a daily pill—it's a lifeline for your baby’s brain development and your own health during pregnancy. Stopping it or skipping doses can raise your risk of miscarriage, preterm birth, or developmental delays in your child. The good news? With the right monitoring and dose adjustments, most women have healthy pregnancies while staying on thyroid meds.
During pregnancy, your body’s demand for thyroid hormone jumps by 30% to 50%. That’s because your placenta makes a hormone called hCG that mimics TSH, and your liver starts clearing thyroid hormone faster. Your TSH levels, the measure of thyroid-stimulating hormone from your pituitary gland, used to assess thyroid function. Also known as thyroid-stimulating hormone, it needs to stay under 2.5 mIU/L in the first trimester—lower than the normal range for non-pregnant adults. If your TSH creeps up, your doctor will likely increase your levothyroxine dose, often within the first 4 to 6 weeks. Many women need their dose adjusted every 4 to 6 weeks until the second trimester, then less often after that.
You’re not alone in this. About 2 to 3 out of every 100 pregnant women have hypothyroidism, and up to half of them are already on medication before getting pregnant. The key is consistency: take your pill on an empty stomach, wait at least 30 to 60 minutes before eating or drinking coffee, and avoid calcium or iron supplements within 4 hours. These common mistakes can block absorption and make your dose ineffective. Your doctor will check your TSH and free T4 levels regularly—usually once per trimester, sometimes more often if you’ve had thyroid issues before.
Some women worry about side effects, but levothyroxine is one of the safest drugs you can take while pregnant. It’s a synthetic version of the hormone your body naturally makes. It doesn’t cross the placenta in harmful amounts—it’s designed to replace what your body can’t produce enough of. The real danger isn’t the medication—it’s untreated low thyroid function. Studies show babies born to mothers with uncontrolled hypothyroidism are more likely to have lower IQ scores and attention problems later in life. That’s why sticking to your plan isn’t just about feeling better—it’s about giving your child the best start possible.
After delivery, your thyroid needs change again. Many women can go back to their pre-pregnancy dose within a few weeks, but some need to stay on the higher dose longer. Your doctor will check your thyroid levels around 6 weeks postpartum to make sure you’re not over- or under-medicated. And if you’re breastfeeding, don’t stop your medication—levothyroxine is safe and passes into breast milk in tiny, harmless amounts.
Below, you’ll find real-world advice from doctors, patients, and clinical guidelines that cut through the noise. Whether you’re newly diagnosed, adjusting your dose, or just trying to understand why your doctor keeps asking for blood tests, these posts give you the facts you need—no fluff, no fear-mongering, just clear guidance on managing thyroid health during one of the most important times in your life.
Thyroid medication doses must increase by 20-30% during pregnancy to support fetal brain development. TSH should be kept under 2.5 mIU/mL in the first trimester, with testing every 4 weeks. Levothyroxine is safe and essential - delaying adjustments can impact your child's IQ.
