How Thyroid Effect On Pregnancy

Pregnancy impacts the functioning of the thyroid gland profoundly and is associated with a 10%–40% increase in the size of the gland (iodine‐replete areas show greater increase), a 50% increase in the production of thyroxine (T4) and triiodothyronine (T3), and a 50% increase in the daily requirement of iodine.

What is the thyroid ?

The gland that is located on the front part of the neck below the thyroid cartilage ( also called Adam’s apple). It produces thyroid hormones, which regulate metabolic rate (how fast calories are consumed to produce energy). These hormones helps in regulating body energy, body temperature, the body’s use of other hormones and vitamins, and the growth and maturation of body tissues.

How is thyroid hormones produced ?

The process of hormone synthesis begins in a part of the brain called the hypothalamus. The hypothalamus releases thyrotropin-releasing hormone (TRH). The TRH travels through the venous plexus located in the pituitary stalk to the pituitary gland, also in the brain.

In response, the pituitary gland then releases thyroid-stimulating hormone (TSH, also called thyrotropin) into the blood. The TSH travels to the thyroid gland and stimulates the thyroid to produce the two thyroid hormones, L-thyroxine (T4) and triiodothyronine (T3). The thyroid gland also needs adequate amounts of dietary iodine to be able to produce T4 and T3, the molecules of which contain four and three atoms of iodine, respectively.

Facts on Thyroid Problems in pregnancy

Diseases of the thyroid gland can result in either production of too much (overactive thyroid disease or hyperthyroidism), too little (under-active thyroid disease or hypothyroidism) thyroid hormone, thyroid nodules, and/or goiter. Thyroid problems are much more common in women than in men.(source)

Problems getting pregnant

When thyroid disease affects the menstrual cycle, it also affects ovulation. This can make it harder for you to get pregnant.
Thyroid problems during pregnancy can cause health problems for the mother and the baby.

The most common cause of an over-active thyroid (hyperthyroidism) is Graves’ disease. If it is untreated you may have lighter, irregular periods and find it difficult to conceive. After treatment, if you are planning to have a baby you should first have a blood test to check your thyroid function. If you are not planning to get pregnant then use a contraceptive during and after treatment, as normal fertility can return extremely quickly

Hypothyroidism in Pregnancy

Hypothyroidism do not ovulate or produce mature eggs in a regular manner, which makes it difficult for them to conceive.
The signs and symptoms of hypothyroidism

  • fatigue,
  • poor attention span,
  • weight gain, numbness,
  • and tingling of the hands or feet
  • are also prominent symptoms of a normal pregnancy.
    Un-diagnosed hypothyroidism during pregnancy increases the chance of stillbirth or growth retardation of the fetus. It also increases the chance that the mother may experience complications of pregnancy such as anemia, eclampsia, and placental abrupt-ion.

How to get cure:

  •  The ideal thyroxine replacement dose (for example, levothyroxine may rise by 25% to 50% during pregnancy. It is important to have regular checks of T4 and TSH blood levels as soon as pregnancy is confirmed; and frequently through the first 20 weeks of pregnancy to make sure the woman is taking the correct medication dose.
  • It is recommended that the levothyroxine dose be adjusted to keep the TSH level < 2.5 mIU/L during the first trimester of pregnancy and < 3 mIU/L during the last two trimesters of pregnancy.

Hyperthyroidism in Pregnancy

Newly diagnosed hyperthyroidism occurs in about 1 in 2,000 pregnancies. Graves’ disease accounts for 95% of cases of hyperthyroidism newly diagnosed during pregnancy.The signs and The signs and symptoms of hyperthyroidism

  • weight loss,
  • vomiting,
  • increased blood pressure,
  • or persistently fast heart rate

Mild or subclinical hyperthyroidism defined as a lower than normal TSH and normal Free T4 level is not dangerous to the mother or baby and does not need to treated. Thyroid tests should be checked again in 4 weeks. However, untreated moderate to severe hyperthyroidism does cause fetal and maternal complications including poor weight gain and tachycardia (an abnormally fast heart rate).

How to get cure:

Propylthiouracil is used during the first trimester to block the synthesis of thyroid hormone and to bring thyroid hormone levels to borderline or slightly higher than normal levels.

Propylthiouracil has a lower risk of some rare fetal malformations compared to methimazole  and is preferred during the critical fetal developmental period during the first trimester. Propylthiouracil is not recommended during the remainder or pregnancy because of the risk of serious hepatitis.

Does Pregnancy Make Goiters Larger?

It is common for a goiter to enlarge slightly during pregnancy. It is more common when the mother lives in an area of iodine deficiency. it is recommended that only prenatal vitamins that contain iodine should be used during pregnancy. If a thyroid nodule is found during pregnancy, new recommendations are not to wait until the end of pregnancy, but to arrange for an evaluation and possible biopsy as soon as possible.

Thyroid goiter is any enlargement of the thyroid that can occur with hyperthyroidism or hypothyroidism but also with benign and malignant (cancerous) nodules. Worldwide, the most common cause of goiter is iodine deficiency.

Postpartum Thyroid Disease 

Some women may have temporary thyroids called postpartum sub-acute thyroids that usually occurs within 3 to 6 months after giving birth. It also may occur after miscarriage. The classic clinical picture is a woman who will first have symptoms of hyperthyroidism with palpitations, anxiety, and weight loss, followed by hypothyroidism with fatigue, constipation, and weight gain, culminating in normal thyroid function in 90% of women of experience this condition.
Women with type I diabetes have a 25% risk of developing postpartum thyroid dysfunction.

The hyperthyroid stage of postpartum thyroids rarely needs treatment. If your symptoms are bothering you, your doctor may prescribe a beta-blocker, a medicine that slows your heart rate. Anti-thyroid medicines are not useful in postpartum thyroids, but if you have Grave’s disease, it may worsen after your baby is born and you may need anti-thyroid medicines.
You’re more likely to have symptoms during the hypothyroid stage. Your doctor may prescribe thyroid hormone medicine to help with your symptoms. If your hypothyroidism doesn’t go away, you will need to take thyroid hormone medicine for the rest of your life.(source)

Thyroid cancer

There are several types of thyroid cancer.

The most common type, papillary thyroid carcinoma, occurs in more than 85% of cases. This type of cancer can be caused by radiation exposure as a child or adolescent, including therapeutic radiation used in the treatment of cancers or in accidents such as the Chernobyl nuclear disaster.

Most of the time, the reason for developing thyroid cancer rates have been increasing steadily by about 6% every year for more than 20 years.

Thyroid cancer is diagnosed after a thyroid ultrasound exam and a needle aspiration biopsy of the nodule.


Is it safe to breastfeed when taking thyroid medicines ?

Certain beta-blockers are safe to use while you’re breastfeeding because only a small amount shows up in breast milk. The lowest possible dose to relieve your symptoms is best.

Only a small amount of thyroid hormone medicine reaches your baby through breast milk, so it’s safe to take while you’re breastfeeding.

However, in the case of anti-thyroid drugs, your doctor will most likely limit your dose to no more than 20 milligrams (mg) of methimazole or, less commonly, 400 mg of PTU.(source) 

Most commonly asked questions :

A lump in your thyroid means that you have thyroid cancer or are an increased risk of developing cancer?

The majority of thyroid nodules aren’t cancerous and never will be. it is always good to get tested if you find the swelling on your neck.

What foods and medications can interact with thyroid medication?

There are numerous foods and medications that interact with levothyroxine. These foods and medications do not need to be avoided completely, but should not be ingested within 4 hours of taking levothyroxine. Some of these foods and medications include iron, calcium, multivitamins, soy, phenytoin, some estrogen products, and some cholesterol-lowering medications. These substances can alter the absorption of thyroid hormone.

Can I have thyroid disease if my thyroid function tests are normal?

It is possible to have thyroid problems despite having normal thyroid function tests. If blood test results show that the thyroid is functioning within normal ranges, patients with symptoms should talk to their doctors to rule out other problems of the thyroid including, autoimmune disorders, thyroid nodules, or thyroid cancer. Further work-up will likely involve checking for antibodies in the blood, ultrasound evaluation of the thyroid, and biopsy of any suspicious thyroid nodules.

Can I drink alcohol while taking levothyroxine?

While various foods and medications affect the absorption of levothyroxine, alcohol has no significant interaction with this medication. Consuming alcohol on a regular basis could lead to liver disease and is not recommended. Because levothyroxine is broken down by the liver, it is possible that alcohol-induced liver dysfunction could change the metabolism of levothyroxine.

What food you should not eat with a hypothyroid problem in pregnancy?

Soy foods: Tofu, tempeh, edamame, etc.
Certain vegetables: Cabbage, broccoli, kale, cauliflower, spinach, etc.
Fruits and starchy plants: Sweet potatoes, cassava, peaches, strawberries, etc.
Nuts and seeds: Millet, pine nuts, peanuts

What food to be taken by a hypothyroid pregnant women

Eggs: Whole eggs are best, as much of the iodine and selenium are found in the yolk, while the whites are full of protein.
Meats: All meats, including lamb, beef, chicken, etc.
Fish: All seafood, including salmon, tuna, halibut, shrimp, etc.
Vegetables: All vegetables are fine to eat. Cruciferous vegetables are fine to eat in moderate amounts, especially when cooked.
Fruits: All other fruits including berries, bananas, oranges, tomatoes, etc.
Gluten-free grains and seeds: Rice, buckwheat, quinoa, chia seeds and flax-seed.
Dairy: All dairy products including milk, cheese, yogurt, etc.

What food you should not eat with a hyperthyroid problem in pregnancy?

Cruciferous vegetables and other types may stop your thyroid from using iodine properly. bamboo shoots, bok choy, broccoli ,Brussels sprouts ,cassava, cauliflower, collard greens, kale, mustard ,rutabaga.

Should every patient with a normal thyroid functions be screened for any thyroid disorders?

Pregnancy is nothing short of a stress test to evaluate thyroid reserve. As pregnancy progresses, the likelihood of hypothyroidism increases. ATA suggests regular TSH monitoring for euthyroid antibody positive woman throughout gestation. TES recommends screening in second trimester as well. However they make no recommendation for euthyroid antibody negative women.

Can thyroid problem during pregnancy affect baby ?

During the first few months of pregnancy, the fetus relies on the mother for thyroid hormones. Thyroid hormones play an essential part in normal brain development. Deprivation of the maternal thyroid hormone due to hypothyroidism can have irreversible effects on the fetus.

What can be the babies complications due to mothers thyroid problem?

Hyperthyroidism, if untreated, can lead to stillbirth, premature birth, or low birth weight for the baby. Sometimes it leads to fetal tachycardia, which is an abnormally fast pulse in the fetus. Women with Graves’ disease have antibodies that stimulate their thyroid gland. These antibodies can cross the placenta and stimulate a baby’s thyroid gland. If antibody levels are high enough, the baby could develop fetal hyperthyroidism, or neonatal hyperthyroidism.

Untreated hypothyroidism, even a mild version, may contribute to pregnancy complications. Treatment with sufficient amounts of thyroid hormone replacement significantly reduces the risk for developing pregnancy complications associated with hypothyroidism, such as premature birth, preeclampsia, miscarriage, postpartum hemorrhage, anemia and abruptio placentae.

How much iodine should ,mother take during pregnancy, who is without any thyroid problem?

Iodine requirement is increased during pregnancy because of increased thyroid hormone production, increased renal iodine excretion, and fetal iodine requirements. Women who had adequate iodine intake before and during pregnancy have adequate iodine stores and therefore have no difficulty in adapting to the increased demands. However, inadequate stores are gradually depleted during pregnancy, leading to deficiency.

As per WHO guidelines, the recommended total dietary intake of iodine is 250 μg/day. At the same time, excessive consumption of iodine should also be avoided due to the potential of fetal hypothyroidism (Wolff–Chaikoff effect) and guidelines advise against exceeding an intake of 500–1100 μg/day.


Pregnancy impacts the functioning of the thyroid gland profoundly and is associated with a 10%–40% increase in the size of the gland (iodine‐replete areas show greater increase), a 50% increase in the production of thyroxine (T4) and triiodothyronine (T3), and a 50% increase in the daily requirement of iodine. These physiological changes can render a pregnant, iodine‐deficient, euthyroid woman in the first trimester hypothyroid during the later stages of pregnancy. It is always better to screen for the thyroid functions when you are planning for pregnancy to avoid latter complications associated with thyroid disease .

For more related articles regarding women and child health:

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Migraine is linked to pregnancy complications- Research proven

New dads tend to suffer from depression and anxiety (Post partum depression in men) !(VIDEO)

Baby Born via Womb Transplant from Dead Donor First in U.S.




Self life hacks

Doctor by profession and blogger by passion

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