The thyroid is a butterfly-shaped gland in your neck. You probably don’t even know it’s there. But if it’s not working properly, you might not be able to conceive or have a healthy pregnancy.
Mary Shomon was one of the lucky women who got pregnant within the first few months of trying. But when she called an obstetrician’s office to make an appointment, the office staff told her it wasn’t necessary for her to see a doctor until her eighth week. “I told them I needed to come in earlier because I have a thyroid problem. And they didn’t know what I was talking about,” she remembers.
Mary insisted on seeing the doctor sooner, and when she did, she found out her thyroid hormone levels were already nearly outside the normal range. If her medication hadn’t been adjusted immediately, Mary would have risked losing the baby. Instead, she had a healthy pregnancy and delivered a baby girl, Julia, who is now a healthy eight year old.
Mary has since become a patient advocate, disseminating information via books and the Web on the under-recognized problem of thyroid disease, especially in women of reproductive age who want to maintain their fertility and get pregnant. “Women are all told to take folic acid before getting pregnant, but no one tells you to get your thyroid checked,” she says.
According to The Thyroid Foundation of America, there are as many as 8 million women in America with untreated thyroid disorders. For those of reproductive age, infertility or miscarriage may be the first sign that something is wrong.
Thyroid Theory
The thyroid is a large, butterfly-shaped gland located in the base of the neck. It manufactures a host of hormones, the most important being thyroxine (T4), which acts as a metabolism master. As more T4 is produced, virtually every cell in the body increases the rate at which it does its job—including those in the heart, which beats faster under the influence of T4. Conversely, when T4 levels fall, metabolism slows down. Ideally, the body maintains the perfect level of T4 hormone, and the perfect rate of metabolism.
The most common thyroid disorders are marked by either too much T4 (hyperthyroidism) or too little T4 (hypothyroidism) in the body. The symptoms reflect the effects of a too-fast or too-slow metabolism. Depending on how severe the imbalance is, the symptoms may be so subtle that the condition goes unrecognized for years. Even worse, doctors may dismiss or discount a woman’s account of her symptoms. This happened to Mary Shomon: Even though she repeatedly visited her family doctor because of unexplained weight gain and heavy fatigue (classic symptoms of a slow thyroid), her doctor didn’t test her thyroid for several months.
Fertility Problems When Things Go Too Slow. . .
Hypothyroidism, the condition of having an underactive thyroid, is the most common thyroid disorder. The slowed-down metabolism associated with it can manifest as constipation, heavier periods, weight gain, decrease in appetite, lethargy, depression, cognitive problems, fatigue, dry skin, cold intolerance, or muscle aches. “But individual patients have different symptoms that vary with severity,” explains Carolyn Coulam, M.D., a reproductive endocrinologist with The Rinehart Center for Reproductive Medicine in Chicago.
Hypothyroidism can cause infertility by preventing ovulation—even when menstrual periods are occurring regularly. Women with undiagnosed hypothyroidism who do conceive have an elevated risk of miscarriage. And even hypothyroid women who’ve already been diagnosed, treated, and stabilized with medication—like Mary Shomon—need to be monitored closely. “Metabolism increases during pregnancy and often the thyroid can’t keep up,” explains Dr. Coulam. “Doses may need to be increased during pregnancy for some women.”
Some women with an underactive thyroid may experience elevated levels of prolactin, the hormone that induces the production of breast milk in postpartum women. Excess prolactin can make conceiving more difficult, again by preventing ovulation. Hypothyroidism’s effects on metabolism can also bring on a condition known as luteal phase defect. The luteal phase is the second half of the monthly cycle, lasting from ovulation to menstruation. It is normally 12 to 16 days long. But if the luteal phase chronically runs shorter than ten days, then there will be fertility problems since the uterine lining can’t build up sufficiently for the embryo to implant, and it will be flushed from the body with the next menstrual period.
Fertility Problems When Things Go Too Fast
The opposite scenario is hyperthyroidism, in which the thyroid gland becomes overactive and the body’s metabolism runs too fast. Signs of hyperthyroidism include more frequent bowel movements, weight loss, irregular periods, increased appetite, insomnia, nervousness, heat intolerance, hand tremors and heart palpitations.
One common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder which tends to run in families and affects the entire thyroid gland. Another cause of an overactive thyroid are so-called “hot nodules” that can form on the gland. In this case, most of the gland continues to perform normally, but the nodule contains cells that produce too much of the T4 hormone.
Whatever the cause of the hyperthyroidism, the result is that the condition can sometimes prevent ovulation and cause infertility. But the bigger problem, according to Celia Dominguez, M.D., of Atlanta’s Emory Clinic, is that when a woman with hyperthyroidism does conceive, her metabolism may be so out of balance that miscarriage or fetal death may result.
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