Hypothyroidism in pregnancy


  1. If I have hypothyroidism during pregnancy, will my baby develop hypothyroidism?
    Maternal hypothyroidism does not cause hypothyroidism in baby. However, you should be treated with thyroid hormone to prevent milder intellectual problems in the baby.
  2. I am tired all the time, but thought that was just due to pregnancy. How do I know the difference?
    If you experience the symptoms listed above in addition to the fatigue, you should alert your endocrinologist who can perform blood tests of thyroid function.


  1. How will treatment effect my pregnancy (fetus)?
    A: Thyroid hormone is important for your health and for the development of your fetus. The treatment is safe and essential for both mother and baby.


  1. Why does my hypothyroidism impact the baby?
    Some of the mother’s thyroid hormone crosses the placenta to provide a hormone supply to the baby until its own thyroid gland starts to function especially in first three months. Evidence is accumulating that your thyroid hormone plays a role in the early development of the fetus, particularly brain development.



  1. I was diagnosed with Graves’ Disease. Will the radioactive iodine treatment for hyperthyroidism affect my ability to get pregnant, and/or have a negative impact on my pregnancy?
    The amount of radiation exposure to your ovaries during treatment is small. There is no evidence that the children of mothers who have been treated with radioactive iodide before pregnancy have an increased incidence of abnormalities. However, most endocrinologists recommend that you wait at least six months after treatment before becoming pregnant. Treatment during pregnancy, however, can affect the baby’s thyroid gland. You should be certain that you are not pregnant prior to treatment with radioactive iodine.



  1. I know that I have hypothyroidism. Will my hormone dose change because of pregnancy?
    Thyroid hormone requirements increase, on average, by about 30% during pregnancy. If you have hypothyroidism and become pregnant, you should immediately consult your Endocrinologist for change in dose. Therefore, thyroid function tests should be checked during pregnancy and thyroid hormone replacement should be adjusted to maintain the TSH level in the normal, or low-normal range (to mimic the normal physiology of pregnancy).


  1. I am planning to become pregnant. Should I be tested for hypothyroidism?
    If you have symptoms of hypothyroidism, or if others in your family have thyroid disease, testing is necessary. If you have any concerns or questions about the possibility of having hypothyroidism, consult your endocrinologist.



  1. I am pregnant now. Should I ask my obstetrician to test me for hypothyroidism?
    At present, thyroid testing is not routinely performed during pregnancy. However, you should discuss any symptoms or concerns with your endocrinologist, and mention any personal or family history of thyroid disease. Recent studies suggest that early diagnosis and treatment of maternal hypothyroidism during pregnancy is beneficial for the developing baby.
  2. Do I need to seek testing for my baby prior to birth? What tests should I request at birth?
    Your baby does not need to best tested before birth as long as the pregnancy is proceeding normally. You should consult your obstetrician about this. In the U.S. and Canada, all babies are routinely screened for a low thyroid level as part of the newborn screening program. This test will be performed prior to leaving the hospital. However, you should tell your pediatrician that you have hypothyroidism. Your pediatrician will decide whether additional testing of your baby is necessary after birth.


  1. If I am being treated for hypothyroidism, can I nurse my baby?
    Very small amounts of L-thyroxine appear breast milk, but will not adversely affect your baby. However, when taking any medication, consult your endocrinologist before you nurse.