Hold control (command on a Mac) and press the + key as many times as necessary to increase the font size.
Hold control (command on a Mac) and press the - key to reduce the font size. - hide

Graves' Disease and Pregnancy - 2010



Graves’ Disease in Pregnancy
by Giuseppe Barbesino, M.D.

Hypothyroidism during pregnancy

At first, your baby relies completely on tiny amounts of thyroid hormone that enter its circulation from your own blood.   Hypothyroidism in a newborn baby or young child may lead to permanent mental retardation and growth impairment.  It is therefore important that your thyroid hormone levels stay well within the normal range during your pregnancy.  If you are already taking thyroid hormone, your TSH should be checked as soon as you become pregnant, with follow up tests completed every 6–12 weeks throughout your pregnancy.

Hyperthyroidism during pregnancy

Some women who develop Graves’ disease will do so while they are pregnant.  The chances of miscarriage and stillbirth rise if hyperthyroidism goes untreated, and the overall risks to you and your baby further increase if the disease persists late in pregnancy.  Therefore, significant hyperthyroidism should be treated.

Since radioactive iodine can destroy the baby’s thyroid, the treatment of choice for an overactive thyroid diagnosed during pregnancy is anti-thyroid medication. Of the two available drugs, propylthiouracil (PTU) is usually preferred early in pregnancy. The other available drug methimazole (Tapazole) has been associated with extremely rare cases of malformations in the fetus. Because the risk of malformations ends after the first trimester, methimazole can be used in the second and third trimester. The goal is first to control your hyperthyroidism and then to use the lowest possible amount of medication to keep your thyroid hormone levels in the high-normal range.

 

If you develop a mild allergy to one anti-thyroid medication, your doctor may switch you to the other. If you develop a more severe drug allergy or have another problem taking the pills, then

you may end up having your hyperthyroidism treated with surgery to remove most of the thyroid. This is usually done in the middle part of pregnancy, but fortunately is rarely necessary.

Typically, hyperthyroidism in pregnancy lessens or resolves completely as the pregnancy progresses. As you near your due date, you may be able to reduce your dosage of anti-thyroid

medication or even stop taking it altogether. If severe hyperthyroidism persists, however, it is important to maintain control of your thyroid levels to avoid developing “thyroid storm” (severe thyrotoxicosis) during labor and delivery.  If this happens, you may need additional treatment with a beta blocker such as propranolol or atenolol and high doses of nonradioactive iodine to control heart rate and other symptoms.

Small doses of beta blockers may be used during pregnancy to control a rapid pulse and other symptoms of hyperthyroidism, especially before surgery.

Thyroid disease in the fetus

Anti-thyroid medications, too much iodine, and, very rarely, maternal thyroid antibodies can all cross the placenta and cause hypothyroidism in your baby. Iodine, which is present in some drugs, including some cough medicines, can cause a goiter in the fetus, making delivery difficult or blocking the baby’s windpipe.  For this reason, drugs containing iodine in high doses should not be used in pregnancy except in special situations.

Too little iodine can be a problem, too. Iodine is necessary for the fetus because it is a part of thyroid hormones.  The increased popularity of low-sodium foods has resulted in a greater number of Americans not getting sufficient iodine.  All pregnant women are therefore advised to take a daily prenatal vitamin containing about 150 micrograms of iodine.

Unfortunately, there is no simple blood test to assess your baby’s thyroid function while you are pregnant. But even if your baby is hypothyroid at birth, immediate treatment with thyroid hormone should allow for normal growth and development. 

Fetal hyperthyroidism occurs occasionally due to transfer of a mother’s thyroid-stimulating antibodies across the placenta. Most often, the mother herself has hyperthyroidism that is being treated with anti-thyroid drugs, which also treat the baby. If you had hyperthyroidism in the past and were treated with radioactive iodine or surgery to remove your thyroid, you are probably no longer hyperthyroid. However, the antibodies may remain in your blood. Since you feel well, your physician may not suspect a problem in your baby. Clues to fetal hyperthyroidism are a fetal heart rate consistently above 160 beats per minute and high levels of thyroid-stimulating antibodies in your blood.

Untreated fetal hyperthyroidism may lead to low birth weight and head size, fetal distress in labor, neonatal heart failure, and respiratory distress. Therefore, if you have ever had Graves’ disease, tell your physician. He or she should test your blood for thyroid-stimulating antibodies late in pregnancy. You may need to take anti-thyroid drugs during pregnancy to treat your baby.

Close follow-up and continued treatment of your baby will be necessary after delivery. Fortunately, your antibodies disappear from your baby’s circulation in the first weeks of life.

 

Used with permission of the author:  Dr. Giuseppe Barbesino, Assistant Professor of Medicine, Thyroid Associates, Massachusetts General Hospital

 

Download as a PDF.

Recent News

Recent Forum Posts

  • What do you think of this theory?

    June 18, 2021, 4:39 p.m.

    (Edited) Hello - Thanks for being flexible on the username to help us avoid confusion with our other admin! I...

  • What do you think of this theory?

    June 17, 2021, 1:57 p.m.

    https://pubmed.ncbi.nlm.nih.gov/31482765/ 2019 study, another perspective on ATD treatment. Note especially...

  • What do you think of this theory?

    June 17, 2021, 12:32 p.m.

    Hi Kimberly—thanks for your reply June 11. Per your advice I’ll update my screen name, ellenb. Do I...

  • What do you think of this theory?

    June 11, 2021, 3:52 p.m.

    Hello and welcome! First, do you mind if we work with you to update your screen name to avoid confusion with...

  • What do you think of this theory?

    June 10, 2021, 6:39 p.m.

    Gianna— Hi, I'm trying to decide on treatment for Graves. Can you tell me— how was your...

  • What do you think of this theory?

    June 6, 2021, 10:10 a.m.

    Hi Sue, and hello everyone! This is my first ever post and I'm happy to be here! I was diagnosed with Grave's...

  • What do you think of this theory?

    June 6, 2021, 8:48 a.m.

    Thanks for the links, Kimberly….. I'll go check them out right now. Actually I don't have celiac...

  • What do you think of this theory?

    June 4, 2021, 4:59 p.m.

    Great to see you! I've not seen research on gluten intolerance and absorption, but there *have* been studies...

  • METHIMAZOLE long term??

    June 4, 2021, 11:47 a.m.

    Hi Conky, I have been on methimazole long term. I was diagnosed in 2013 and in 2019 my trabs was finally...

  • What do you think of this theory?

    June 4, 2021, 9:08 a.m.

    Wow - thank you for that info. I really know very little about mast cells and histamine but it's definitely...

  • What do you think of this theory?

    June 4, 2021, 4:03 a.m.

    This makes sense. Mast cells, which secrete histamine, affect T3 and gluten intolerance also has a histamine...

  • What do you think of this theory?

    June 3, 2021, 4:57 p.m.

    Been a looooooong time since I posted…. so grateful Kimberly is still here keeping this board alive!...

  • New TED diagnosis

    June 1, 2021, 6:45 p.m.

    Hello - I've not heard of patients using TEPEZZA (TM) *just* for swelling, but you might also check out our...

  • How do I support and rebuilt with my partner after years of Graves?

    June 1, 2021, 6:41 p.m.

    Hello and welcome - hopefully, others will chime in here, and you might also check out our Facebook group,...

  • Thyroid and soy

    June 1, 2021, 6:36 p.m.

    Hello and welcome - I think the concern with soy is more about its impact on absorption when you take your...

Questions? Problems? Please contact us at [email protected] or 877-643-3123.

GDATF on Facebook

Support the GDATF and become a member today!

© 2021 Graves' Disease & Thyroid Foundation