Thyroid Disease And Pregnancy
Thyroid disease affects different aspects of pregnancy and postpartum health for the mother and the newborn child. There have been varied and contradicting practices with regards to thyroid disease and pregnancy. As a result a group of endocrinologists came together to publish a journal containing clinical guidelines for the management of thyroid problems during pregnancy and during the postpartum period. The creation of this group came about over a two-year period and their findings were published in the Journal of Endocrinology and Metabolism, the August of 2007 issue. This journal represents the methods and practices of endocrinologists all over the world.
Some of the main components of that journal are being discussed below. The points bear crucial implications for women who are diagnosed with thyroid disease during their pregnancy or even at the postpartum stage. Some of the information also has a bearing on women who develop thyroid disease before they get pregnant.
Hypothyroidism & Pregnancy
The condition of hypothyroidism in a mother or an unborn child can cause serious health problems on the unborn baby. If a woman is aware of her condition as properly diagnosed hypothyroidism, she should reconsider trying to get pregnant or avoid maternal hypothyroidism altogether.
If a woman should develop hypothyroidism prior to her pregnancy and it has been properly diagnosed by a doctor or endocrinologist, her thyroid medication will need to be adjusted so that the thyroid stimulating hormone (TSH) level goes no higher than 2.5 prior to entering pregnancy.
A woman diagnosed as hypothyroid during her pregnancy should undergo treatment immediately. The goal is to restore her thyroid levels back to normal as soon as possible. Upon entering the first trimester, her thyroid-stimulating hormone (TSH) level should be held at less than 2.5. Upon entering the second and third trimester, her thyroid-stimulating hormone (TSH) should be maintained at less than 3.0. Thyroid function tests need to be reviewed and re-evaluated within 30 to 40 days after the initial diagnosis.
When a pregnant woman reaches week four to six, her thyroid medication dosage will almost always need to be increased. It is possible that her dosage will increase by anywhere from thirty to fifty percent.
Some women have a thyroid auto-immunity as in cases where she has been previously examined and found to be positive for thyroid antibodies. Woman who have an auto-immunity and who possess normal thyroid stimulating hormone (TSH) levels in early stages of pregnancy can still be at risk of becoming hypothyroid at any point in the pregnancy. It is recommended that she be monitored regularly throughout the pregnancy for elevated thyroid stimulating hormone (TSH).
If a woman is diagnosed with subclinical hypothyroidism which involves a thyroid stimulating hormone (TSH) level above normal with normal free T4 levels, her condition can lead to a negative health outcome for her and her unborn child. Immediate treatment of the mother can help to ensure a healthier pregnancy and birth outcome. However, treatment has not been proven to guarantee long-term neurological development of the baby. In spite of this, experts believe that the possible benefits of treatment still outweigh any possible risks if the mother went without treatment. The consensus is that treatment is recommended even in women with subclinical hypothyroidism.
Once childbirth has occurred, most women who have been diagnosed with hypothyroidism will need to have their medication dosage reduced.
Hyperthyroidism & Pregnancy
It has been found that hyperthyroidism can be brought on by Graves’ disease. Transient hyperthyroidism can also trigger hyperemesis gravidarum, which is a condition of pregnancy that causes severe morning sickness. The diagnosis involves determining whether a woman has a goiter, tests positive for thyroid antibodies or both.
If a pregnant woman’s hyperthyroidism is triggered by Graves’ disease or nodules are found in the gland, she should begin treatment for hyperthyroidism immediately. Generally, pregnant women are given anti-thyroid medication as part of treatment especially when initially diagnosed.
The most common antithyroid medication given usually during the first trimester is propylthiouracil. Propylthiouracil is generally the drug of choice because methimazole contains has a slightly higher risk of birth defects. Methimazole is used, but it is only prescribed if propylthiouracil is not available or if a woman is experiencing complications with it.
There are situations where surgery may be the only recommended method for treatment instead of drugs. They are:
If there is a severe negative reaction to anti-thyroid drugs. If a woman requires an extremely high dosage to control her hyperthyroidism. Uncontrolled hyperthyroidism remains despite treatment.
If the above cases are evident, surgery is recommended usually during the second trimester. The second trimester for this operation poses less risk to the unborn child and danger to the pregnancy.
Treating subclinical or mild hyperthyroidism has not been shown to improve or better the outcome of pregnancy. Therefore, treating subclinical or mild hyperthyroidism is not because of the potential negative effects on the unborn child.
Note: Radioactive iodine should never be administered to any woman who is or may be pregnant.
Antibodies, Graves’ Disease and Newborns
There are two antibodies in a mother that can cross the placenta and affect the unborn child’s thyroid gland. They are called TSH receptor-stimulating or TSH receptor-binding antibodies. If a woman is diagnosed positive for any of these antibodies while pregnant, her child can be born with hyperthyroidism. It is very important that these antibodies be measured in both women who have Graves’ disease or who have given birth previously to newborn children who developed Graves’ disease. It may be necessary to treat the mother with anti-thyroid drugs in order to reduce any risk to the newborn child.
If a woman has elevated TSH receptor-stimulating or TSH receptor-binding antibodies and is treated with anti-thyroid drugs, a doctor should conduct a fetal ultrasound evaluation. This scan will search for any evidence of dysfunction in the thyroid gland of the still developing baby. Such would include finding any evidence of slow growth and enlargement in the baby’s thyroid.
If a new mother has been diagnosed with Graves’ disease, her newborn child should still be evaluated after birth for any dysfunction in its thyroid gland.
Pregnancy with Severe Morning Sickness and Hyperthyroidism
Hyperemesis gravidarum is severe morning sickness that may also include dehydrations and significant weight loss. All pregnant women diagnosed with hyperemesis gravidarum should have their thyroid gland examined for any dysfunction.
If a woman is diagnosed with overt hyperthyroidism due to Graves’ disease and gestational hyperthyroidism with substantially elevated thyroid hormone levels treatment may be required.
Thyroid Nodules, Thyroid Cancer & Pregnancy
A fine-needle aspiration (FNA) biopsy evaluation is recommended for pregnant women with thyroid nodules measuring larger than 1 cm in size.
Once a pregnant woman is diagnosed with malignancy or cancerous thyroid nodules and they are such nodules are found during the first or second trimester, surgery should be recommended in the second trimester.
Note: Well-differentiated thyroid cancers grow at a much slower rate. If the evaluation or biopsy shows the cancer to be papillary or follicular without any evidence of advanced disease, a woman may be able to choose having the surgery after childbirth.
A pregnant woman previously diagnosed with thyroid cancer or a woman (as in the above case) diagnosed with a well-differentiated thyroid cancer opting to have surgery after her child is born can still receive treatment that can help to suppress thyroid stimulating hormone (TSH). Though her thyroid stimulating hormone (TSH) level may be suppressed, it would still be detectable. The desirable situation is to have free T4 or total T4 levels remain within the normal range for the pregnancy.
Note: Radioactive iodine should never be administered to women who are breastfeeding.
Women who are receiving therapeutic doses of radioactive iodine should wait a minimum of six months and up to a year before becoming pregnant. This will ensure stability of thyroid function and that the cancer is in remission.
Postpartum Thyroid Problems After Pregnancy
A thyroid evaluation should be conducted three to six months after a woman has given birth if she has already tested positive for thyroid peroxidase antibodies.
In women with type 1 diabetes, postpartum thyroiditis is three times more likely to occur. That being the case, woman with type 1 diabetes should have thyroid evaluation three months and six months after childbirth.
Women who already have a history of postpartum thyroiditis have a significantly increased risk of developing hypothyroidism within five to ten years after a postpartum thyroiditis episode. Any women that fall into this group should have their thyroid checked and evaluated annually.
Screening for Thyroid Dysfunction During Pregnancy
In particular, women who face a higher risk of thyroid disease should be screened and evaluated. It is recommended that these evaluations occur in women who are having an infertility evaluation.
It is also recommend that women who fall into the at-risk groups below be evaluated.
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