Hypothyroidism in Pregnancy

Published in August 2020
Compiled by Team ISAR 2020-2021

The Thyroid gland is a butterfly shaped gland present in the middle of the neck. It produces two hormones that are secreted into the blood – thyroxine (T4) and triiodothyronine (T3). It is an important endocrine gland for proper metabolic health.

Hypothyroidism is a condition of underactive thyroid gland, in which the thyroid gland is not able to produce enough thyroid hormones for proper metabolic functions of the body. It is either due to auto immune condition where your own body kills the cells which make this hormone or due to the deficiency of iodine in certain areas and because of that deficiency your body is not able to make enough thyroid hormone. The trans Gangetic plane of India is a regions where iodine deficiency is very common.

Worldwide Prevalence: 3 -- 5%
Prevalence in India: 10 – 12 %
Out of these the majority have subclinical hypothyroidism.

Causes of hypothyroidism:

  • Primary hypothyroidism (95% cases) – Due to problems in the thyroid gland
  • Secondary hypothyroidism (5% cases) -- Due to problems in the pituitary or hypothalamus

Types of hypothyroidism:

  • Subclinical hypothyroidism –
  • TSH levels – Increased
  • T3 levels -- Normal
  • T4 levels -- Normal
  • Overt hypothyroidism --
  • TSH levels -- Increased
  • T3 levels -- Decreased
  • T4 levels -- Decreased

Symptoms of hypothyroidism:

  • If you are suffering from thyroid hormone deficiency, you could feel few of the following symptoms:
  • Fatigue (tiredness)
  • Myalgia (muscular pain and aches)
  • Breathlessness
  • Excess Weight gain
  • Dry skin and nails
  • Swelling in the legs
  • Hair fall
  • Excess feeling of cold
  • Irregular menstruation (usually heavy and frequent bleeding)
  • Subfertility

Pregnancy outcomes with uncontrolled hypothyroidism:

  • Once you become pregnant your chances for certain complications increase:
  • Miscarriage
  • Fetal growth restriction
  • Low birth weight babies
  • Poor brain development in baby
  • Poor developmental milestones in baby
  • Poor attention span in baby
  • Anemia in mother
  • Placental abruption in mother
  • Post partum bleeding, Etc.

How to diagnose?

  • Blood to be evaluated for – TSH
  • Free T4 Anti TPO-Antibody

When to treat hypothyroidism in pregnancy?

  • In Overt hypothyroidism
  • To be treated when upper limit of normal TSH exceeds the following trimester specific values –
  • In first trimester – 2.5mIU/L
  • In second and third trimester -- 3 mIU/L

In Subclinical Hypothyroidism

  • To be treated in the following conditions –
  • When TSH > 10 mIU/L
  • Presence of Anti TPO-Antibody

Treatment of hypothyroidism

  • A thorough evaluation is recommended by an Endocrinologist. Thyroid hormone replacement may be prescribed by the doctor in the form of Levothyroxine.
  • This is usually given in a Dose of 1.6 µg/kg body weight
  • To be taken on an empty stomach
  • Repeat TSH after 4-6 weeks and adjust dose.
  • Levothyroxine is to be continued in the antenatal and post partum period after adjusting the dose.
  • Regular monitoring of TSH levels are to be done in the post partum period and dose of levothyroxine is to be adjusted accordingly.
This content is copyright of ISAR India.
For more information write to isar.office@gmail.com
ISAR Fact Sheets