Thyroid disorder may not show symptoms until pregnancy

Q: I’m five months pregnant and was just diagnosed with hypothyroidism. I’ve never had thyroid problems before. Could this diagnosis be connected to my pregnancy? Will the hypothyroidism go away after I have my baby?

A: It’s likely that the hypothyroidism was triggered by your pregnancy, but the underlying cause probably isn’t the pregnancy itself. Some women have a thyroid disorder that doesn’t show any symptoms until they become pregnant. Once symptoms appear, it’s important to receive treatment and continue followup care for six to nine months after the baby is born. You’ll also need periodic checkups after that to monitor your thyroid function, especially if you become pregnant again.

Your thyroid is a small, butterfly-shaped gland at the base of the front of your neck. The hormones that the thyroid gland makes — triiodothyronine, or T3, and thyroxine, or T4 — affect all aspects of metabolism. They maintain the rate at which your body uses fats and carbohydrates, help control body temperature, influence heart rate, and help regulate the production of proteins. Research has shown that about 10 per cent of young women have a thyroid disorder that, although it doesn’t cause problems before pregnancy, does produce symptoms during pregnancy. Women who have a thyroid disorder often are found to have high concentrations of antithyroid antibodies in their bodies. After childbirth, the antibody level usually increases and may lead to temporary altered thyroid function. This also may occur during pregnancy.

As in your case, this thyroid disorder often leads to hypothyroidism due to low levels of thyroid hormones in the body. Common symptoms can be hard to spot during pregnancy because they mimic signs of pregnancy, such as weight gain, fatigue and constipation. Others more obvious during pregnancy include increased sensitivity to cold, dry skin, a puffy face, muscle weakness, hoarseness, joint pain or stiffness, and difficulty with concentration or memory.

Treatment with thyroid hormone (levothyroxine) is crucial because untreated hypothyroidism can affect fetal development and maternal health.