Hypothyroidism in Pregnancy

Hypothyroidism in pregnancy is usually caused by Hashimoto’s disease. This is a condition of chronic inflammation of the thyroid gland.

Like Graves’ disease, Hashimoto’s disease is an autoimmune disorder. Here the immune system attacks the thyroid causing inflammation and interfering with its ability to produce thyroid hormones.

Effects of Hypothyroidism on Mother and Baby

Uncontrolled hypothyroidism during pregnancy can lead to:

  • Preeclampsia
  • Anemia- Lowered red blood cells in the body, which prevents the body from getting enough oxygen.
  • Miscarriage
  • Low birth weight
  • Stillbirth

Because thyroid hormones are crucial to fetal brain and nervous system development, uncontrolled hypothyroidism, especially during the first trimester, can affect the baby’s growth and brain development.

Diagnosing Hypothyroidism in Pregnancy

Like hyperthyroidism, hypothyroidism is diagnosed through a careful review of symptoms and measurement of TSH and T4 levels.

Symptoms of hypothyroidism in pregnancy include:

  • Extreme fatigue
  • Cold intolerance
  • Muscle cramps
  • Constipation
  • Problems with memory or concentration

High levels of TSH and low levels of free T4 generally indicate hypothyroidism. Because of normal pregnancy-related changes in thyroid function, test results must be interpreted with caution.

The TSH test showing high levels of TSH and normal free T4 imply Sub Clinical Hypothyroidism. This is a mild form of hypothyroidism that has no apparent symptoms.

Treating Hypothyroidism in Pregnancy

Hypothyroidism is treated with synthetic thyroid hormone called thyroxine, a medication which is identical to the T4 made by the thyroid. Women with preexisting hypothyroidism will need to increase their pre-pregnancy dose of thyroxine to maintain normal thyroid function. Thyroid function should be checked every 6 to 8 weeks during pregnancy. Synthetic thyroxine is safe and necessary for the well-being of the fetus if the mother has hypothyroidism.

Because the thyroid uses iodine to make thyroid hormone, iodine is an important mineral for a mother during pregnancy. During pregnancy, the baby gets iodine from the mother’s diet. Choosing iodized salt over plain salt and prenatal vitamins containing iodine will ensure this need is met.

Read about guidelines for managing Hyperthyroidism during pregnancy.

Medical Advice (Q&As) on “Hypothyroidism in Pregnancy

  1. Ghaneema

    I am pregnant at 10 weeks of gestational age
    The result of TSH is 3.3 mlU/L .
    The doctor saw the result. She started thyroxine 50 micro gram immediately, but today for follow up my 1st doctor was not available so another doctor saw me and told me that I should stop taking thyroxine that the level of TSH is normal for pregnant in 1st trimester.
    What shall I do now doctor? I am afraid if I stop the medicine it would harm my baby?
    Thank you

    1. Buddy M.D. Post author

      Let us know how long did you take thyroxine? Also, what was your TSH level at the follow up visit, when your doctor asked you to stop the medicine?

      Hypothyroid states during pregnancy are to be managed on a regular basis. TSH is measured at a regular basis and the dose of the medicine is constantly altered.

      The aim is to keep the TSH somewhere between 0.1 and 2.5 mIU/L. This aim is achieved by making constant alterations in the dose of thyroxine being taken.

      Read more about the desired TSH levels in pregnancy.

  2. Asma

    My Dad is 60 years old, had diabetes and hypertension 8 years ago, on Metformin 1000mg twice daily and Gliclazide 160mg twice daily and Amlodipin 10mg once daily.
    HbA1c from 7.6 to 8 %
    Blood pressure 163/92
    Would he change his treatments either doses or types for his diabetes and hypertension?

  3. Ekta Singh

    Dear Sir/Madam, I am 31 weeks pregnant this time and I am 27 years old. It is my first pregnancy. My thyroid profile as below:

    —–20 Dec 2013——

    TSH – 6.070 range 0.39–5.55 uU/ml

    FSH – 10.0 range 4.5–168.8 miU/ml

    ——–21 feb 2014——–(LMP- 20 Feb 2014)

    TSH – 6.27 range 0.27–4.20 uIU/ml

    = thyronorm 50 mcg start taking

    ——-03 March 2014——-

    TSH – 6.27 range 0.27–4.20 uIU/ml
    FT4 – 1.35 range 0.80–2.30 ng/dl

    =increase thyronorm 75 mcg
    = Last menstrual period 20 Feb 2014

    ——17 April 2014——

    TSH – 2.670 range 0.39–5.55 uIU/ml

    Tt3 – 1.31 range 0.79–1.58 ng/ml

    Tt4 – 10.0 range 4.0–11.0 ug/dl

    =thyronorm 75 mcg continue

    ——–20 July 2014——

    TSH – 1.675 range 0.39–5.55 uU/ml

    Tt3 – 1.93 range 0.79–1.58 ng/ml

    Tt4 – 15.6 range 4.0–11.0 ug/ dl

    =thyronorm 75 mcg continue
    Gyne doctor refer to medicine doctor for treatment. After seeing the result med doctor stop the thyronorm for one months.

    ——–22 Aug 2014———

    TSH – 2.91 range 0.550–4.780 uIU/ml

    Free t3 – 3.03 range 2.30–4.20 pg/ml

    Free t4 – 1.26 range 0.89–1.76 ng/dl

    = medicine doc says no need of medicine.

    ———14 Sept 2014———-

    TSH – 2.576 range 0.550–4.780 uIU/ml

    Free T3 – 2.91 range 2.30–4.20 pg/ml

    Free T4 -1.14 range 0.89–1.76 ng/ml

    =med doc says every thing is in mid range no need of medicine.

    = again for test after the delivery me and my baby also.

    = I am going in right way are not for me and my baby growth ?
    When I should again test the thyroid profile.
    I saw in internet TSH should be below the 2.5

    Please reply. I am in interior hill area.

    1. Buddy M.D. Post author

      You may go with your doctor’s advice. Your TSH levels are much within the range. This is enough.

      It would be important to monitor your baby’s growth (by U/S) throughout pregnancy.


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