Link between hypothyroidism and pregnancy

A reduced functionality of the thyroid gland during pregnancy can cause many symptoms both for mother and the baby so it’s necessary that proper diagnosis and therapy are taken in time. According to the directions of the American Association for Thyroid, the reference value of the TSH hormone for women who are not pregnant has a maximum recommended value of about 4mIU/L. This number is a result of years of trial and error and group efforts of scientists who were experts in thyroid diseases, gynecologists, labors lead by this organization. If the laboratory doesn’t have the reference values of TSH for a specific trimester, these are generally accepted as good: First trimester – 0.1 – 2.5, second trimester – 0.2 – 3.0 and the third trimester 0.3 – 3.0.

In pregnancy, hypothyroidism is determined with this value being above 2.5, with a reduced value of the free thyroxin (FT4). If the woman has a normal FT4 and TSH is above 10 during pregnancy, this is also considered to be a real example of hypothyroidism. Subclinical hypothyroidism is a condition defined with values of TSH in between 2.5 and 10, with a regular level of FT4. With women who have a recommended amount of iodine, hypothyroidism is commonly caused with the auto-immune Hashimoto’s disease. According to directives, the antibodies reacting on thyroid peroxidase are a characteristic of Hashimoto’s disease and are found in about 50% of women with a subclinical hypothyroidism with over 80% of women suffering from clinical hypothyroidism.

Controlled treatment of hypothyroidism during pregnancy

When we discuss the topic of hypothyroidism and pregnancy, it’s important to know why is this such a critical state and what needs to be done in order for the pregnancy to follow through without any major issues. To start with, it’s recommended to increase the overall concentration of T4 by about 20-50% so that all hormonal needs in pregnancy are safe and sound. This happens with women who have a healthy thyroid as well, as hormones are really important for everything to go by smoothly. However, with women who are treating their hypothyroidism and get pregnant, the thyroid gland might not always be ready to respond to requests on increasing the T4, which requires an increased dosage of medicine.

According to directives, the increase in requests begin somewhere in between 4 and 6 weeks into pregnancy and can typically grow all the way up to 20 weeks of pregnancy, experiencing a plateau until birth. About 50-80% of women suffering from hypothyroidism will need this increase in medicine dosage during pregnancy. The dosage of levothyroxine needs to be increased as soon as pregnancy is confirmed. For women who use therapy once per day and are found in the condition, as soon as there is a doubt about pregnancy it is recommended to add two pills more on a weekly basis.

The level of the hormones needs to be checked every 6 weeks, which is a period required for the levels to find their new balance. If the balance stays the same, it’s important to know why is it happening before increasing the medicine dosage.

About the author

Rani Vyas

Rani Vyas

I'm a Medical Consultant Doctor with a keen interest in Medical bioinformatics and genuinely intriguing way of presenting boring medical knowledge in an enchanting and eye catching way.

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