Hyperthyroidism is a thyroid condition that affects five to ten percent of women after childbirth. Here's what you need to know about the connection between your thyroid and pregnancy.

By Maressa Brown

After giving birth, you expect your body to be different. That's just postpartum life, right? But certain changes that occur after childbirth aren't exactly par for the course for all women. Specifically, thyroid conditions that are triggered by pregnancy.

Your thyroid, a butterfly-shaped gland located at the base of your neck, regulates a lot of basic functions, such as metabolism. It does this by constantly releasing a steady amount of hormones called thyroxine into the bloodstream, explains Zev Williams, M.D., Ph.D., chief of the Division of Reproductive Endocrinology and Infertility and associate professor of obstetrics and gynecology at Columbia University Medical Center. When the body needs more energy – like during pregnancy – the thyroid gland produces more hormones.

Two pregnancy-related hormones – human chorionic gonadotropin (hCG) and estrogen – cause higher thyroid hormone levels in the blood. But for some women, an immune system malfunction can cause the thyroid to go into overdrive, resulting in hyperthyroidism. This literally means overactive thyroid.

Thyroid Test with Doctor and Pregnant Woman
Credit: NotarYES / Shutterstock

Hyperthyroidism Symptoms After Pregnancy

Those suffering from hyperthyroidism may encounter many of the following symptoms:

  • Rapid weight loss
  • Heat intolerance
  • Excessive hunger
  • Hair loss
  • A bulge in the base of the neck
  • Hot flashes
  • Sweating
  • Trembling
  • Diarrhea
  • Nervousness
  • Hyperactivity
  • Emotional instability and irritability
  • Fatigue
  • Insomnia
  • Restlessness
  • Racing heart

What Causes Postpartum Thyroid Issues?

There are two thyroid conditions diagnosed postpartum that can cause hyperthyroidism: postpartum thyroiditis and Graves’ disease.

Postpartum Thyroiditis

Postpartum thyroiditis occurs when the thyroid becomes inflamed within the first year after childbirth. "The immune system is relatively suppressed during pregnancy," explains Kevin Borst, D.O., an endocrinologist at Cleveland Clinic in Ohio. "After delivery of a baby, there is an immune system 'rebound,' which allows susceptible women to be at risk for a condition called postpartum thyroiditis. It's thought to occur in about 5 percent of women.”

The condition generally starts out with a hyperthyroid phase, which occurs two to six months after delivery, Dr. Borst said. It’s then followed by a hypothyroid (underactive thyroid) phase, occurring at three to 12 months postpartum. “Symptoms of underactive thyroid would include excessive fatigue, intolerance to cold, constipation, and dry skin,” Dr. Borst explains. “In about 10 percent of women, this phase is permanent and requires medication; otherwise treatment is usually not necessary in this condition.” In the other 90 percent of women, normal thyroid function returns within 12-18 months of the onset of symptoms.

Risk factors for postpartum thyroiditis: Given that postpartum thyroiditis is rare and its symptoms (like anxiety, insomnia, and fatigue) are often mistakenly attributed to the stress of having a newborn and postpartum mood disorders, postpartum thyroiditis can be difficult to recognize.  “It is more common in women who have other autoimmune disorders, such as type 1 diabetes, or who have the presence of thyroid antibodies in their blood called TPO antibodies,” Dr. Borst explains. (A thyroid peroxidase antibody test can confirm the presence of these antibodies.) Twenty percent of women who experienced postpartum thyroiditis after their first pregnancy will have a recurrence with subsequent pregnancies.

Graves’ Disease

Most hyperthyroidism associated with pregnancy is caused by an autoimmune condition called Graves’ disease, in which a malfunction in the body’s immune system attacks the thyroid and causes it to make more thyroid hormone than your body needs. Graves’ affects about one in 200 people in the U.S. and is seven to eight times more common in men than women.

Graves’ is likely encoded in DNA at birth, according to Vanessa Ghaderi, M.D., chief of endocrinology with the Kaiser Permanente South Bay Medical Center in Harbor City, California. But she adds that an event later in life, like pregnancy, can trigger the immune system and lead to the onset of clinical disease.

“Women are typically diagnosed 3-6 months after delivery,” Dr. Borst notes. “The symptoms of hyperthyroidism are typically more severe than in postpartum thyroiditis, and the thyroid gland is often palpable.” In other words, enlargement of the thyroid may cause Graves’ patients to notice a lump in their throat where the thyroid is located. This is referred to as a goiter.

Risk factors for Graves’ disease: Being a woman and pregnancy are two main risk factors for Graves’, but a woman’s family history/genetics, history of autoimmune disorders, age (those under 40 are more susceptible), emotional or physical stress, and history of cigarette smoking also increase risk of disease.

Treatments for Hyperthyroidism

The best treatment for thyroid issues after pregnancy depends on a mom's age, physical condition, the underlying cause of the hyperthyroidism, personal preference, and the severity of the disorder. Here are a few options.

Radioactive iodine: This is absorbed by the thyroid gland, where it causes the gland to shrink. With this treatment, the symptoms usually subside within three to six months.

Anti-thyroid medications: If hyperthyroidism stems from Graves’ disease, a patient will be treated initially with anti-thyroid medications, explains Dr. Borst. These can address symptoms within six to 12 weeks "and should be used at the lowest doses possible while a woman is nursing,” he says. "The pediatrician should be made aware that the mother is taking this medication." Some medications can cause liver damage, so you should consult your doctor on what treatment is best for you.

Beta blockers: These are commonly used to treat high blood pressure and can address hyperthyroid symptoms like rapid heart rate and help prevent palpitations.

Thyroid surgery: In some cases, surgery to remove the thyroid may be recommended.

Ultimately, working one-on-one with a doctor to pinpoint the cause of postpartum thyroid issue is key to coming up with a winning treatment plan.