Thyroid disease is a group of disorders that affects the thyroid gland. The thyroid is a small, butterfly-shaped gland in the front of the neck that makes two thyroid hormones. Thyroid Disease on Pregnancy Thyroid hormones control how the body uses energy, so they affect how nearly every organ in the body works, including the heart.
Sometimes the thyroid makes too much or too little of these hormones. When there is an excess of thyroid hormone, hyperthyroidism occurs and can cause many of the body’s functions to speed up. “Hyper” means that the thyroid is more active than normal. Get additional information on hyperthyroidism in pregnancy . When there is a deficiency of thyroid hormone, hypothyroidism occurs and can cause many of the body’s functions to be reduced. “Hypo” means that the thyroid is less active than normal. Get additional information on hypothyroidism in pregnancy .
If you have thyroid problems, you can still have a healthy pregnancy and protect your baby’s health by having your thyroid function tested and taking any medications your doctor prescribes.
What role do thyroid hormones play in pregnancy?
Thyroid hormones are crucial for the normal development of the baby’s brain and nervous system. During the first trimester, the first 3 months of pregnancy, the baby depends on the mother’s supply of thyroid hormone, which comes through the placenta NIH external link . Around week 12, the baby’s thyroid begins to work on its own, but it doesn’t make enough thyroid hormone until 18 to 20 weeks of pregnancy.
Two pregnancy-related hormones, human chorionic gonadotropin (hCG) and estrogen, cause higher levels of thyroid hormone in the blood. During pregnancy, the thyroid enlarges slightly in healthy women, but not enough to be felt by a health care professional during a physical exam.
Thyroid Disease on Pregnancy
Thyroid Disease on Pregnancy Thyroid problems can be difficult to diagnose during pregnancy due to higher levels of thyroid hormones and other symptoms that occur with both pregnancy and thyroid disorders. Some symptoms of hyperthyroidism or hypothyroidism are easier to spot and may prompt your doctor to check you for these thyroid conditions.
Postpartum thyroiditis , another type of thyroid disease, can develop after the baby is born.
hyperthyroidism in pregnancy
What are the symptoms of hyperthyroidism in pregnancy?
Some symptoms and signs of hyperthyroidism are common in normal pregnancies, including a faster heart rate, tiredness, and difficulty coping with the heat.
Other symptoms and signs that may suggest hyperthyroidism:
- fast and irregular heartbeat
- trembling in the hands
- unexplained weight loss or lack of normal weight gain during pregnancy
What causes hyperthyroidism in pregnancy?
Hyperthyroidism in pregnancy is usually caused by Graves’ disease and occurs in 1 to 4 of every 1,000 pregnancies in the United States. 1Graves’ disease is an autoimmune disorder. With this disease, the immune system produces antibodies that cause the thyroid to make too much thyroid hormone. This antibody is known as thyroid-stimulating immunoglobulin, or TSI. Graves’ disease may first appear during pregnancy. However, if you already have Graves’ disease, your symptoms may improve in the second and third trimesters. Some parts of the immune system become less active as the pregnancy progresses, so your immune system makes less TSI. This may be the reason why the symptoms improve. Graves’ disease usually worsens again during the first few months after delivery, when TSI levels rise again treat your hyperthyroidism . 1 Very high levels of thyroid hormone can harm the health of you and your baby.
Rarely, hyperthyroidism in pregnancy is associated with hyperemesis gravidarum External link , which is severe vomiting and nausea that can cause weight loss and dehydration. Experts believe that this severe vomiting and nausea during early pregnancy is caused by high levels of hCG. High levels of hCG can cause the thyroid to make too much thyroid hormone. This type of hyperthyroidism usually goes away during the second half of pregnancy.
Less commonly, one or more nodules, or lumps, on the thyroid make too much thyroid hormone.
How can hyperthyroidism affect my baby and me?
Untreated hyperthyroidism during pregnancy can cause:
- spontaneous abortion
- premature birth
- low birth weight
- pre-eclampsia: a dangerous increase in blood pressure in late pregnancy
- thyroid crisis: a sudden and severe worsening of symptoms
- congestive heart failure
- Rarely, Graves’ disease can also affect the baby’s thyroid, causing it to make too much thyroid hormone. Even if your hyperthyroidism has been cured by treatment with radioactive iodine to destroy thyroid cells or surgery to remove the thyroid, your body still makes the TSI antibody. When levels of this antibody are high, TSI can reach the baby’s bloodstream. Just as TSI caused your thyroid to make too much thyroid hormone, it can also cause your baby’s thyroid to make too much of it.
Tell your doctor if you’ve had surgery or radioactive iodine treatment for Graves’ disease, so your TSI levels can be checked. If they are very high, the doctor will monitor the baby for thyroid-related problems later in the pregnancy.
An overactive thyroid in a newborn can cause:
- rapid heartbeat, which can lead to heart failure
- premature closure of the soft spot on the baby’s skull
- little weight gain
- Sometimes an enlarged thyroid can press against a baby’s windpipe and make it hard for him to breathe. If you have Graves’ disease, your health care team should carefully monitor you and your baby.
How do doctors diagnose hyperthyroidism in pregnancy?
Your doctor will review your symptoms and do some blood tests to measure your thyroid hormone levels. The doctor may also look for antibodies in your blood to see if Graves’ disease is causing your hyperthyroidism. Get additional information about thyroid tests and what the results mean.
How do doctors treat hyperthyroidism during pregnancy?
If you have mild hyperthyroidism during pregnancy, you probably don’t need treatment. If your hyperthyroidism is related to hyperemesis gravidarum, you only need treatment for vomiting and dehydration.
If your hyperthyroidism is more severe, your doctor may prescribe anti thyroid medications, which cause your thyroid to make less thyroid hormone. This treatment prevents too much thyroid hormone from entering the baby’s bloodstream. You may want to see a specialist, such as an endocrinologist or maternal-fetal medicine expert, who can carefully monitor your baby to make sure he’s getting the right dose.
Doctors usually treat pregnant women with the anti thyroid drug propylthiouracil NIH external link (PTU) during the first 3 months of pregnancy. Another type of anti thyroid drug, methimazole NIH external link , is easier to take and has fewer side effects, but is slightly more likely to cause serious birth defects than PTU. Birth defects with any type of medication are rare. Doctors sometimes switch to methimazole after the first trimester of pregnancy. Some women don’t need anti thyroid medication after the third trimester.
Small amounts of anti thyroid medicine pass into the baby’s bloodstream and decrease the amount of thyroid hormone the baby makes. If you take anti thyroid medications, your doctor will prescribe the lowest dose possible to prevent hypothyroidism in the baby, but enough to treat high levels of thyroid hormone that can also affect the baby.
In some people, anti thyroid medications can cause side effects such as:
- allergic reactions such as skin rashes and itching
- very rarely, a decrease in the number of white blood cells, which can make it harder for
- the body to fight infection
- rarely liver failure
Stop taking anti thyroid medicine and call your doctor right away if you have any of these symptoms while taking it:
- yellowing of the skin or the whites of the eyes (jaundice)
- dull pain in the abdomen
- permanent sore throat
- If the doctor does not contact you the same day, you should go to the nearest emergency room.
You should also contact your doctor if you experience any of the following symptoms for the first time while taking anti thyroid medications:
- increased tiredness or weakness
- loss of appetite
- skin rash or itching
- easy bruising
- If you are allergic or have severe side effects to antithyroid medications, your doctor may consider surgery to remove part or most of the thyroid gland. The best time for thyroid surgery during pregnancy is in the second trimester.
Radioactive iodine treatment is not an option for pregnant women because it can damage the baby’s thyroid gland.
hypothyroidism in pregnancy
What are the symptoms of hypothyroidism in pregnancy?
The symptoms of an underactive thyroid are often the same for pregnant women as they are for other people with hypothyroidism. Symptoms include:
- difficulty tolerating the cold
- muscle cramps
- severe constipation
- memory or concentration problems
What causes hypothyroidism in pregnancy?
Hypothyroidism in pregnancy is usually caused by Hashimoto’s disease and occurs in 2 to 3 out of 100 pregnancies. 1 Hashimoto’s disease is an autoimmune disorder. In Hashimoto’s disease, the immune system produces antibodies that attack the thyroid, causing inflammation and damage that makes it difficult for it to produce thyroid hormones.
How can hypothyroidism affect my baby and me?
Untreated hyperthyroidism during pregnancy can cause:
pre-eclampsia: a dangerous increase in blood pressure in late pregnancy
low birth weight
very rarely, congestive heart failure
These problems occur more often with severe hypothyroidism.
Because thyroid hormones are so important to a baby’s brain and nervous system development, untreated hypothyroidism, especially during the first trimester, can cause low IQ and problems with normal development.
How do doctors diagnose hypothyroidism in pregnancy?
Your doctor will review your symptoms and do some blood tests to measure your thyroid hormone levels. Your doctor may also look for certain antibodies in your blood to see if Hashimoto’s disease is causing your hypothyroidism. Get additional information about thyroid tests and what the results mean .
How do doctors treat hypothyroidism during pregnancy?
Treatment for hypothyroidism involves replacing the hormone that your own thyroid can no longer produce. Your doctor will probably prescribe levothyroxine NIH external link , a medication for thyroid hormone that is the same as T 4 , one of the hormones your thyroid normally makes. Levothyroxine is safe for the baby and is especially important until the baby can make its own thyroid hormone.
The thyroid produces a second type of hormone, T 3 . Early in pregnancy, T3 can not enter the baby’s brain like T4 can . Whatever T3 the baby’s brain needs is made from T4 . T3 is included in many thyroid medications made from animal thyroid, such as Armor Thyroid , but it is not helpful for a developing baby’s brain. These drugs contain too much T3 and too little T4 and should not be used during pregnancy. Experts recommend using levothyroxine (T 4 ) only during pregnancy.
Some women with subclinical hypothyroidism, a mild form of the disease with no clear symptoms, may not need treatment.
If you had hypothyroidism before you became pregnant and are taking levothyroxine, your dose may need to be increased. Most thyroid specialists recommend taking two additional doses of thyroid medication per week, starting right away. Contact your doctor as soon as you know you are pregnant.
Your doctor will likely test your thyroid hormone levels every 4 to 6 weeks during the first half of your pregnancy, and at least once after 30 weeks. 1 Your dose may need to be adjusted several times.
What is postpartum thyroiditis?
Postpartum thyroiditis is an inflammation of the thyroid that affects about 1 in 20 women during the first year after childbirth 1 and is more common in women with type 1 diabetes. The inflammation causes stored thyroid hormone to leak from the gland thyroid. Initially, this leakage increases hormone levels in the blood and causes hyperthyroidism. Hyperthyroidism can last up to 3 months. Later, an injury to the thyroid can cause it to become underactive. Hypothyroidism can last up to a year after giving birth. However, in some women, hypothyroidism does not go away.
Not all women who have postpartum thyroiditis go through both phases. Some only go through the hyperthyroid phase, and others only go through the hypothyroid phase.
What are the symptoms of postpartum thyroiditis?
The hyperthyroid phase often has no symptoms, or only mild symptoms. Symptoms may include irritability, difficulty coping with heat, tiredness, sleep problems, and rapid heartbeat.
Symptoms of the hypothyroid phase can be confused with the “baby blues,” symptoms of which include tiredness and moodiness, which sometimes occurs after the baby is born. Symptoms of hypothyroidism may also include difficulty tolerating cold, dry skin, difficulty concentrating, and tingling in the hands, arms, feet, or legs. If these symptoms occur in the first few months after your baby is born, or if you develop postpartum depression NIH external link , talk to your doctor as soon as possible.
What causes postpartum thyroiditis?
Postpartum thyroiditis is an autoimmune disease similar to Hashimoto’s disease. If you have postpartum thyroiditis, you may have already had a mild form of autoimmune thyroiditis that flares up after giving birth.
How do doctors diagnose postpartum thyroiditis?
If you have symptoms of postpartum thyroiditis, your doctor will order blood tests to check your thyroid hormone levels.
How do doctors treat postpartum thyroiditis?
The hyperthyroid stage of postpartum thyroiditis rarely needs treatment. If your symptoms bother you, your doctor may prescribe a beta-blocker, which is a medicine that slows your heart rate. Anti thyroid medications for postpartum thyroiditis aren’t very effective, but if you have Graves’ disease, it may get worse after the baby is born and you may need them.
You are more likely to have symptoms during the stage of hypothyroidism. Your doctor may prescribe thyroid hormone medications to help relieve your symptoms. If your hypothyroidism does not go away, you will need to take thyroid hormone medicine for the rest of your life.
Is it safe to breastfeed while taking beta blockers, thyroid hormone, or anti thyroid medications?
Certain beta-blockers are safe to use while you’re breastfeeding because only a small amount passes into breast milk. It is best to use the lowest dose possible to relieve symptoms. Only a small amount of thyroid hormone medicine passes to the baby through breast milk, so it is safe to take while you are breastfeeding. However, for anti thyroid medications, your doctor will likely limit your dose to no more than 20 milligrams (mg) of methimazole or, less commonly, 400 mg of PTU.
Thyroid disease and diet during pregnancy
What should I eat during pregnancy to help my baby’s and my thyroid function properly?
Iodine is an important mineral for you during pregnancy because your thyroid uses it to make thyroid hormone. During pregnancy, the baby gets iodine from her diet. She will need to consume more iodine during pregnancy, about 250 micrograms per day. 1 Dairy products, seafood, eggs, meat, poultry, and iodized salt, which is salt with iodine added, are good sources of iodine. Experts recommend taking a prenatal vitamin with 150 micrograms of iodine to make sure you’re getting enough, especially if you don’t use iodized salt. 1You also need more iodine while breastfeeding, since your baby gets iodine from breast milk.
However, excess iodine from supplements such as seaweed can cause thyroid problems. Talk to your doctor about an eating plan that’s right for you and what supplements you should take. Get additional information on a healthy diet and nutrition during pregnancy External link .
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