Should Pregnant Women Have a Thyroid Test?

If you are pregnant and experiencing fatigue, dry skin, sleep loss, or weight loss, it may be worthwhile to find out whether you are a candidate for a thyroid test – these symptoms, while common in pregnant women, may be caused by underactivity (hypothyroidism) or overactivity (hyperthyroidism) of the thyroid gland.

If untreated during pregnancy, both conditions have been shown to result in higher risks for miscarriage, premature birth, preeclampsia, and even impaired intelligence in the child (in the case of hypothyroidism). But does such risk necessarily warrant a universal recommendation for thyroid tests in pregnant women? Ingfei Chen explores an ongoing debate on this issue in a New York Times article.

The thyroid gland produces hormones that regulate many important aspects of our bodies, including metabolism, body weight and heart rate. When there is too much of this thyroid-stimulating hormone (TSH), the pregnant woman suffers from hyperthyroidism and experience poor sleep, weight loss, and nervousness after giving birth. On the other hand, when the thyroid gland is underactive, the resulting hypothyroidism causes fatigue, weight gain and dry skin. Both conditions are manifested in very subtle symptoms but are risk factors for dangerous pregnancy complications.

While both an overactive and an underactive thyroid spell trouble for pregnant women, hypothyroidism is the more common and worrisome condition. Hypothyroidism, affecting 10 to 20% of women of childbearing age, is often undiagnosed but hampers fetal brain development. A study done 10 years ago reports that 19% of children born to women with untreated hypothyroidism had an IQ of 85 or lower, whereas the same measure was only 5% for those born to mothers with a healthy thyroid.

Although risks of an imbalanced level of TSH are known, the medical field is currently split on whether there is sufficient existing evidence for the benefits of treating the condition, and subsequently, of recommending universal screening. Studies are underway to track pregnant women with healthy and underactive thyroids, and their children will be tested for IQ. Until scientists arrive at conclusive results, the general clinical policy is to recommend a thyroid test to high-risk women (for example, a woman with family history of thyroid problems). However, more doctors have begun recommending the test to normal-risk expecting mothers, and many think that evidence for universal screening will soon be available, according to Dr. Stagnaro-Green, an endocrinologist at Touro University College of Medicine in New Jersey.