The test is positive, the joy is immense, and then the gaze falls on the pill bottle next to the toothbrush. If you have a thyroid condition, you immediately wonder: Does this harm the child? The short answer is no, as long as the thyroid is well-regulated. It becomes tricky when no one is watching.
Why the Child Relies on Your Thyroid
In the first weeks of pregnancy, the unborn child does not yet produce its own thyroid hormone in significant amounts. It receives thyroxine from the mother. This hormone is important for brain development, among other things. At the same time, the mother’s demand increases: Due to pregnancy hormones and the larger blood circulation, the gland has to work harder.
A healthy thyroid can manage this without difficulty. A weakened one, such as in Hashimoto’s thyroiditis, reaches its limit more quickly. Then TSH levels rise, and this can be measured in the blood.
Check Before Pregnancy
The easiest way is to clarify the values before conception. This is especially true if you are already taking levothyroxine, if Hashimoto or another thyroid disease is known, or if there are thyroid problems in the family. It’s also worth discussing this beforehand after surgery or radioiodine therapy on the thyroid.
Professional societies recommend that women being treated for hypothyroidism aim for a TSH level in the lower normal range, often a value below about 2.5 mIU/l is mentioned. Whether and how your target is adjusted is decided by your doctor. Adjusting the dosage independently is not a good idea, in either direction.
Continue Taking the Pill, But Report Early
This is the point where many become uncertain. Levothyroxine is explicitly intended during pregnancy. Stopping is the mistake, not continuing. The demand usually increases already in the first weeks, often significantly for many women. Therefore, guidelines recommend contacting the practice immediately after a positive test so that the dosage can be adjusted, not just at the next routine appointment.
After that, TSH is usually monitored more closely, about every four weeks in the first half of pregnancy. The exact rhythm depends on your situation. After birth, the demand often decreases back to previous levels, and this should also be monitored by a doctor. How to manage the intake in daily life is discussed in the article about Levothyroxine in Daily Life. With iron and calcium supplements, which often come during pregnancy, the usual spacing from the thyroid pill applies.
Slightly Elevated TSH: A Borderline Case That Raises Questions
The finding of “latent hypothyroidism” particularly unsettles many: elevated TSH, normal free hormones. Experts do not fully agree on this. The guidelines differentiate based on how high the TSH is and whether thyroid antibodies (TPO antibodies) are detectable. With positive antibodies, treatment is more likely, while without them, in cases of only slightly elevated values, it is more common to wait and monitor.
What follows is a case-by-case decision. A single lab value is not sufficient for this. How to interpret a TSH result is explained in the article on TSH Values.
And What About Hyperthyroidism?
Hyperthyroidism also belongs in the hands of specialists before becoming pregnant or at the latest immediately afterward. Some medications for hyperthyroidism are not suitable in early pregnancy, and an excess of hormones puts both mother and child at risk. A change or a pause should only occur after consultation. Never start something new or stop on your own.
For clarification: In the first trimester, the pregnancy hormone hCG can temporarily stimulate the thyroid, causing TSH to decrease slightly. This is often harmless, but it is a reason to assess values in context and not to hastily diagnose a condition.
Iodine, Selenium, and What Else is on the Shelf
The need for iodine increases during pregnancy, as iodine is a building block of thyroid hormones. Many professional societies therefore recommend iodine supplements for pregnant and breastfeeding women, provided there are no contraindications. In cases of Hashimoto or hyperthyroidism, this may look different. Therefore, ask beforehand whether and in what form iodine is suitable for you.
For selenium, iron, or vitamin supplements from the drugstore, the rule is: More is not better. There is no confirmed benefit for selenium in thyroid diseases during pregnancy.
When You Should See a Doctor
Contact your doctor promptly if you are pregnant or want to become pregnant and are taking thyroid medications, if you haven’t been monitored for a while, or if you experience new symptoms like fatigue, feeling cold, palpitations, tremors, or unintentional weight loss. A noticeably enlarged neck should also be evaluated.
You need immediate medical help for severe abdominal pain or bleeding, persistent rapid heartbeat with shortness of breath, or fainting. In an emergency, call 112.
Frequently Asked Questions
Does Hashimoto Affect Fertility?
An untreated hypothyroidism can disrupt the cycle and make it difficult to conceive. With good regulation, the chances are generally normal. The data on Hashimoto without hypothyroidism is less clear, so it’s worth discussing with your gynecologist or endocrinologist.
Can I Take Levothyroxine During Pregnancy?
Yes. It is the standard for a treatable hypothyroidism and is identical to the body’s own hormone. The dosage is adjusted by the doctor.
Do I Need to Consider Anything While Breastfeeding?
Levothyroxine can also be continued during breastfeeding. Discuss a follow-up appointment for TSH after birth, as the demand changes again.
Read Also
- Recognizing Hypothyroidism: Fatigue, Feeling Cold, Weight Gain, and What It Could Mean
- Understanding TSH Values: What Thyroid Values Indicate
- Hashimoto’s Thyroiditis: When the Immune System Attacks the Thyroid
- Taking Thyroid Hormones: Daily Life with Levothyroxine
This article is for informational purposes only and does not replace medical advice.
Sources
- Alexander E. K. et al.: 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid 2017;27(3):315–389.
- Lazarus J. et al.: 2014 European Thyroid Association Guidelines for the Management of Subclinical Hypothyroidism in Pregnancy and in Children. European Thyroid Journal 2014;3(2):76–94.
- Chaker L., Bianco A. C., Jonklaas J., Peeters R. P.: Hypothyroidism. The Lancet 2017;390(10101):1550–1562.