Conditions & Treatments

Hypothyroidism and Pregnancy

Hypothyroidism is a condition marked by an underactive thyroid gland and may occur during pregnancy

Hypothyroidism and Pregnancy

Facts about hypothyroidism and pregnancy

Hypothyroidism is a condition marked by an underactive thyroid gland and may be present during pregnancy. Many symptoms of hypothyroidism are similar to pregnancy symptoms. For example, fatigue, weight gain, and abnormal menstruation are common to both.

What are the symptoms of hypothyroidism?

Hypothyroidism is a common condition, which can go undetected if symptoms are mild. Hypothyroidism means the thyroid is underactive, producing insufficient amounts of thyroid hormones. Symptoms of hypothyroidism may be mild and may start slowly. The following are the most common symptoms of hypothyroidism:

  • Feeling tired

  • Unable to stand cold temperatures

  • Hoarse voice

  • Swelling of the face

  • Weight gain

  • Constipation

  • Skin and hair changes, including eyebrows

  • Carpal tunnel syndrome (hand tingling or pain)

  • Slow heart rate

  • Muscle cramps

  • Trouble concentrating

  • Irregular menstrual periods

The symptoms of hypothyroidism may resemble other conditions or medical problems. Always consult your doctor for a diagnosis.

How does hypothyroidism affect the fetus?

During the first few months of pregnancy, the fetus relies on the mother for thyroid hormones. Thyroid hormones are important in normal brain development and growth of the fetus. Hypothyroidism in the mother can have long-lasting effects on the fetus. 

How is thyroid function tested?

Screening for hypothyroidism involves a blood test that measures thyroid hormone (thyroxine, or T4) and serum TSH (thyroid-stimulating hormone) levels. Hypothyroidism is often suspected when TSH levels are above normal and T4 levels are below normal. Always consult your doctor for a diagnosis.

Who should undergo thyroid function screening?

Routine screening for hypothyroidism during pregnancy is not recommended. A pregnant woman with symptoms of hypothyroidism, a history of hypothyroidism, or with related conditions (for example, diabetes) should be screened.

How is hypothyroidism treated during pregnancy?

Thyroid hormone replacement therapy is used to treat the mother. Dosage of thyroid hormone replacement therapy is based on the individual's levels of thyroid hormones.  Thyroid hormone levels may change during pregnancy.   And, the thyroid replacement dosing may also change. The treatment is safe and essential to both mother and fetus. Routine screening for all newborns includes a test of thyroid hormone levels.

Treatment Programs

Massachusetts General Hospital understands that a variety of factors influence patients' health care decisions. That's just one reason why we're dedicated to ensuring patients understand their diagnosis and treatment options. Because a single option might not serve all patients, we offer a wide range of coordinated treatments and related services across the hospital. Patients should consult with their primary care doctor or other qualified health care provider for medical advice and diagnosis information.

Select a treatment program for more information:

MassGeneral Hospital for Children

  • Pediatric Endocrine Program and Diabetes Center
    The Pediatric Endocrinology Program and Diabetes Center at MassGeneral Hospital for Children is an international referral center for the management of pediatric diabetes and endocrine disorders in children and adolescents.
Obstetrics and Gynecology

  • Reproductive Medicine Program
    The Reproductive Medicine Program at the Massachusetts General Hospital Department of Obstetrics and Gynecology provides sophisticated, compassionate care for reproductive health problems, placing the highest emphasis possible on patient safety.

View all departments

Departments and Centers at Mass General have a reputation for excellence in patient care. View a list of all departments.