What is Graves disease during pregnancy?
Graves disease is an autoimmune condition. Named for the 19th-century physician Robert Graves who first described it, Graves disease is characterized by hyperthyroidism (an overactive thyroid gland), due to the immune system producing antibodies (immunoglobulins) that stimulate the thyroid to release too much of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). This accelerates your metabolism, producing a range of symptoms and other effects throughout your body. The effects of excessive thyroid hormone levels can include fertility difficulties, but if you do become pregnant your hyperthyroidism can worsen, because of increasing levels of the pregnancy hormone, beta-human chorionic gonadotropin (ß-hCG), whose chemical structure is similar to that of another hormone, thyroid-stimulating hormone (TSH), whose job is to stimulate the thyroid gland when stimulation is needed. Levels of ß-hCG peak at the end of the first trimester, however, causing increased thyroid activity. An increase in levels of estrogen also accelerates the thyroid. The hormonal stimulation of the thyroid is good if everything is working correctly in the body, but it is bad if you are already hyperthyroid for some other reason, such as Graves disease.
How common is Graves disease during pregnancy?
Graves disease accounts for most cases of hyperthyroidism (beyond the normal pregnancy increase in thyroid hormones), which occurs in 2 per 1,000 pregnancies.
How is Graves disease during pregnancy diagnosed?
Hyperthyroidism due to Graves disease produces various symptoms, including heart palpitations, nervousness, increased appetite, eye discomfort, gastrointestinal disturbances, feeling that you are hot, fatigue or muscle weakness, and difficulty sleeping. Some of the symptoms can overlap with symptoms of pregnancy, but the physical examination can reveal signs such as protruding eyeballs, a large or tender thyroid, an irregular heartbeat, and inadequate weight gain for your stage of pregnancy, or even weight loss. You should gain 1-2 kilograms (2 – 5 pounds) over the first trimester, or about 0.5 kg (1 lb) per week. Suspicion of hyperthyroidism will lead the doctor to order blood tests, initially for levels of TSH and whats called free T4 (T4 hormone that is not bound to a special protein called Thyroid-binding globulin [TBG]). Next, you will be tested for antithyroid antibodies, which if present would enable the diagnosis of Graves disease.
Does Graves disease cause problems during pregnancy?
Graves disease accelerates your metabolism, causing symptoms that often include nervousness, excessive appetite, weight loss, gastrointestinal disturbances, eye discomfort, fatigue or muscle weakness, and difficulty sleeping. You may also feel as though you are too hot. If you are pregnant with Graves disease, you may fail to gain enough weight. Excess thyroid hormones stimulate the heart to beat too fast constantly, which strains your heart and can lead to arrhythmias (fast and/or irregular heartbeats, which you may feel as palpitations) and also can cause blood clots. All of this can lead to acute coronary syndrome (ACS) (a heart attack) and even heart failure. The hyperthyroidism of Graves disease also entails an elevated risk for a couple of complications, particular to pregnancy. One of these complications is hyperemesis gravidarum (HG), a severe form of pregnancy nausea and vomiting, which also is related to increases in ß-hCG levels. The other complication is preeclampsia, featuring high blood pressure and dysfunction of an internal organ, usually the kidney.
Does Graves disease cause problems for the baby?
Since Graves disease interferes with your weight gain during pregnancy, the fetus is at risk of low-birth-weight, plus there is an elevated risk of spontaneous abortion (miscarriage), preterm labor, and stillbirth. During the first trimester, the embryo/fetus does not make its own thyroid hormones, but the maternal thyroid hormones cross the placenta in very small quantities, enough to meet the babys needs. On the other hand, thyroid-stimulating antibodies of Graves disease cross the placenta fairly easily, and this can happen throughout pregnancy. Thus, once a fetus can make its own thyroid hormones (during the second trimester), stimulation by the antibodies can cause excessive production of fetal thyroid hormones. This leads to whats called fetal thyrotoxicosis, and, when born, the baby can have neonatal thyrotoxicosis. This means toxicity from excessive amounts of the hormones T3 and T4, which has dangerous consequences for various organ systems, just as it does in adults.
What to consider about taking medications when you are pregnant or breastfeeding:
- The risks to yourself and your baby if you do not treat the Graves disease
- The risks and benefits of each medication you use when you are pregnant
- The risks and benefits of each medication you use when you are breastfeeding
What should I know about using medication to treat Graves disease during pregnancy?
Women with Graves disease during pregnancy require medications to treat symptoms, such as rapid heartbeat (tachycardia). To slow your heart rate, doctors may prescribe a beta-blocker medication. Outside of pregnancy, the most effective treatment for Graves disease is with iodine-131, a radioactive isotope that gets absorbed into the thyroid gland, which it destroys by emitting gamma rays. After the thyroid is destroyed, the person must take thyroid hormones every day on a long-term basis. However, iodine-131 is contraindicated in pregnancy because the radiation dosage is fairly high. Two other medications work by reducing thyroid activity: propylthiouracil (PTU) and methimazole. Of these two, methimazole is contraindicated during early pregnancy because it can cause birth defects. PTU is thus the treatment of choice for pregnant women. However, it can produce rare, but severe, complications, including aplastic anemia, a potentially life-threatening condition, and also severe liver problems. Because of these potential complications, your doctor may change the medication from PTU to methimazole during the latter part of pregnancy, when it is not thought to produce birth defects. In determining the dosage of your medication, doctors will titrate the drug, meaning that they will tweak the dosing and timing of when you take the drug based on your levels of TSH in your blood. Generally, the goal will be to reduce your thyroid hormone levels enough to make you feel better by eliminating, or dramatically reducing, your symptoms, but leaving you a little bit hyperthyroid, rather than bringing your thyroid activity to normal non-pregnancy levels, since doing that can cause some problems for the baby.
Who should NOT stop taking medication for Graves disease during pregnancy?
First of all, if you are being treated with iodine-131, you should not get pregnant until your treatment is completed. You should discuss any desire to change your anti-thyroid medicat
ion regimen with your doctor, since getting dosing and desired effects just right is fairly difficult. As for medications to treat symptoms, such as beta-blockers to slow your heart, you should never stop taking such medications abruptly, but rather discuss any concerns with your doctor.
What should I know about choosing a medication for my Graves disease during pregnancy?
It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.
You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.
What should I know about taking a medication for my Graves disease when I am breastfeeding?
Research suggests that methimazole might be a safer choice than PTU during breastfeeding, but controversy surrounds the question of whether you should nurse at all while you are being treated for Graves disease.
What alternative therapies besides medications can I use to treat my Graves disease during pregnancy?
If anti-thyroid medications are not adequate to improve your condition, thyroidectomy, surgical removal of the thyroid, is the next option. Subsequently, you would then need to take thyroid hormones on a long-term basis.
What can I do for myself and my baby when I have Graves disease during pregnancy?
It is very important to follow the instructions of your physician.
Resources for Graves disease in pregnancy:
For more information about Graves disease during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations: