Graves’ Disease and Pregnancy

Graves’ disease is an autoimmune disorder that causes hyperthyroidism. It is the most common form of overactive thyroid, which causes many of your body’s functions to speed up.

If a woman with Graves’ disease becomes pregnant, the disease can affect both the pregnancy and the health of the mother. Pregnancy may also trigger Graves’ disease in some women. In addition, the risk of developing the disease is seven times higher in the 12 months after giving birth, according to the federal Office on Women’s Health.

Graves’ disease occurs in about 1 in 1,500 women who are pregnant, and it causes roughly 80 percent of all cases of maternal hyperthyroidism. In addition, roughly 30 percent of young women with Graves’ disease were pregnant in the year prior to the onset of their symptoms.

Graves’ disease runs in families, so if you have a family member with the condition, be sure to talk to your doctor if you’re pregnant or planning to conceive. Your doctor may want to check your thyroid levels regularly throughout your pregnancy. Your baby will also be screened for thyroid issues shortly after birth to determine if postnatal treatment is required.

The most common cause of Graves’ disease in a newborn is Graves’ disease in the mother, even if the mother has been successfully treated for Graves’. (1,2)

Symptoms of Graves’ disease typically decrease as pregnancy progresses. (Since Graves’ is an autoimmune phenomenon, it often gets better during pregnancy because of a state of maternal immunosuppression that protects the baby.) Graves’ disease generally becomes worse during the first three months after giving birth.

Common symptoms of Graves’ disease include weight loss, anxiety, tremors, heat sensitivity, sweating, increased appetite, goiter (enlarged thyroid gland), changes in heartbeat, chest pains, difficulty breathing, muscle weakness, difficulty sleeping, and fatigue.

A condition known as Graves’ ophthalmopathy (also known as thyroid eye disease) affects eye function, and its symptoms can include bulging eyes, tearing, pain or pressure in the eyes, light sensitivity, a gritty sensation in the eyes, double vision, or vision loss.

Graves’ disease can affect pregnancy, including these complications:

• Miscarriage
• Preterm birth
• Poor fetal growth
• Fetal thyroid dysfunction
• Maternal heart failure
• Preeclampsia (high blood pressure)
• Infertility in women and men (if the disease goes untreated) (3)

If Graves’ disease worsens during pregnancy, a woman can experience a very severe form of hyperthyroidism known as thyroid storm. Symptoms include diarrhea, dehydration, fever, fast or irregular heartbeat, and shock. Thyroid storm can be fatal, so it’s important to seek emergency care immediately if you experience any of these symptoms. (4)

The treatment of Graves’ disease during pregnancy will depend on your individual symptoms, the severity of the condition, as well as how far your pregnancy has progressed. Women with Graves’ disease are often advised to postpone conception and use contraception until the disease is controlled. Women with difficult-to-control Graves’ who are on high doses of antithyroid medications often choose definitive therapy, such as surgery to remove the thyroid gland, prior to conception.

Anti-Thyroid Medications

Your doctor may prescribe antithyroid medications if the benefits of taking them appear to outweigh the risks. Methimazole (Tapazole) and propylthiouracil (PTU) are the two antithyroid drugs used in the United States to treat hyperthyroidism. Both of these medications can cross the placenta and potentially cause birth defects and hypothyroidism in the fetus. (2) Doctors often recommend the lowest possible dose of antithyroid medication to minimize the risks.

“We used to think that the antithyroid drug methimazole caused birth defects and that PTU didn’t,” says Douglas Ross, MD, a professor of medicine at Harvard Medical School and co-director of thyroid associates at Massachusetts General Hospital. “A few years ago, a large study from Denmark also showed that PTU does cause birth defects, although they are much less severe than methimazole birth defects.” (5)

Birth defects caused by methimazole are often life-threatening and can include choanal atresia (blockage of the nasal passage), esophageal atresia (the upper part of the esophagus does not connect with the lower part), aplasia cutis (absence of skin), umbilical cord defects, or omphalocele (abdominal organs outside the body).

Birth defects caused by PTU can include anatomical anomalies (abnormalities) in the face or neck region and in the urinary system. Such abnormalities generally require surgical treatment but are less severe than the defects caused by methimazole. (6)

“At least in my practice, this information has led most women to decide that they don’t want to take antithyroid drugs at all if they have Graves’ disease and they want to get pregnant,” says Dr. Ross. “And so they choose to do definitive therapy — more frequently the surgery, because they’re in a hurry to get pregnant, than radioactive iodine — to definitively get rid of their thyroid.”

Beta-Blockers

Beta-blockers, a class of drugs commonly used to lower blood pressure, are also used to control the so-called hyperadrenergic symptoms of Graves’ disease, such as anxiety, irritability, rapid heart rate, tremors, and sweating.

While beta-blockers are commonly used during pregnancy, there’s conflicting evidence regarding the risks associated with taking them. If you are prescribed a beta-blocker during pregnancy or are already taking one when you become pregnant, discuss the relative risks and benefits of these drugs with your doctor.

Surgery

A thyroidectomy (surgery to remove all or part of the thyroid gland) is sometimes performed to treat Graves’ disease. After surgery, patients may be prescribed thyroid hormones, as most people will develop hypothyroidism (underactive thyroid) after the surgery. Some women opt to have a thyroidectomy prior to trying to conceive. Surgery poses risks if performed at different points in a pregnancy, so talk to your doctor about the risks and alternatives.

Radioactive Iodine

Radioactive iodine treatment is not recommended for pregnant or nursing women, although some women choose to undergo radioactive iodine treatment before they try to conceive. People who choose radioactive iodine therapy will develop hypothyroidism, which is easier to treat and causes fewer health complications than hyperthyroidism.

If you’re a woman of childbearing age and are considering radioactive iodine treatment, make sure to take a pregnancy test before you begin it, and ask your doctor how long you should wait after the treatment is complete before you try to conceive.

No Treatment

While treating Graves’ disease during pregnancy comes with risks, so does foregoing treatment during pregnancy. Women who do not control their Graves’ disease are almost 10 times more likely to have a baby with low birth weight. They are also 16 times more likely to deliver preterm and 5 times more likely to develop preeclampsia and experience stillbirth.

If you have Graves’ disease and want to have a baby, speak to your doctor about the best way to have a healthy pregnancy while also managing your disease.

Both methimazole and PTU cross into breast milk, so doctors typically recommend limiting the dose and that nursing mothers take their medication after breastfeeding an infant. In addition, if you’re taking one of these drugs, your doctor will probably want to monitor your thyroid and your baby’s thyroid function for several months after birth.

If you are taking antithyroid medications at the time of delivery, it’s important that you continue taking them unless your doctor advises otherwise. Mothers experiencing remission from Graves’ disease are still at risk for symptoms returning up to a year after delivery.

If you have Graves’ disease and are planning to become pregnant, it’s imperative that you create a pregnancy plan with your obstetrician, endocrinologist, and other necessary specialists. Many women with Graves’ disease have healthy babies, and the best chance for a healthy pregnancy and delivery is early planning and coordination with a treatment team. Don’t hesitate to talk to your doctor today about prepregnancy treatment options and how you can manage Graves’ disease and also protect your child during pregnancy.