Autoimmune Thyroid Disease and Pregnancy Follow-up

Updated: Oct 07, 2016
  • Author: Dotun A Ogunyemi, MD; Chief Editor: George T Griffing, MD  more...
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Follow-up

Further Outpatient Care

Hyperthyroidism

Pregnant women with hyperthyroidism should be monitored monthly. Important parameters include vital signs (specifically the pulse rate), weight, FT4 and TSH concentrations, and measures of fetal well-being. The woman's pulse should be maintained below 100 bpm. Maternal weight gain should be appropriate for the mother's prepregnancy weight. TSH levels can be maintained near the low limit of normal as long as the patient is clinically euthyroid. FT4 values should be maintained at the upper limit of normal to ensure that the fetus' requirements are adequately met.

Fetal monitoring during pregnancy is essential. Fetal thyrotoxicosis is suggested when the fetal heart rate is faster than 160 bpm. Ultrasonography may reveal intrauterine growth retardation, advanced bone age, and craniosynostosis. Thyroid-stimulating autoantibodies can cross the placenta and activate the fetal thyroid gland.

In all pregnant women with Graves disease, TSI levels should be measured in the third trimester. A high TSI value is most likely to be associated with fetal thyrotoxicosis. Neonates born to mothers with Graves disease should be evaluated for hyperthyroidism. Approximately 1% of these babies have hyperthyroidism. If left untreated, their mortality rate can be as high as 30%.

All patients' TSH and FT4 levels should be evaluated after delivery. Women can continue taking ATDs while breastfeeding.

Hypothyroidism

Patients with newly diagnosed hypothyroidism should receive TSH testing every 4 weeks, and their dosage of T4 should be adjusted as needed. The T4 replacement dosage increases by 30% by the 10th week of gestation and by 48% by the 20th week.

In all pregnant women with preexisting hypothyroidism, TSH levels should be measured at 6-8 weeks' gestation. Subsequent TSH measurements may be obtained at 16-20 and 28-32 weeks' gestation. After delivery, the dosage of T4 should be reduced to the prepregnancy amount.

Antenatal fetal surveillance may be beneficial. Delivery should be considered at term. In general, women should go past dates.

Long-term follow-up care of patients with hypothyroidism is mandatory.

Postpartum thyroiditis

Patients with PPT should receive long-term follow-up care because PTT frequently recurs with subsequent pregnancies.

Patients with significantly elevated levels antimicrosomal antibodies, a family history of hypothyroidism, or a prominent goiter are at the greatest risk for developing permanent hypothyroidism.

TSH levels should be measured at least once a year.

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Further Inpatient Care

Treatment of maternal or fetal complications

Patients with clinically significant maternal or fetal complications from hyperthyroidism or hypothyroidism should be admitted to the hospital.

Management of thyroid storm

Patients with thyroid storm should be admitted to an intensive care unit. Thyroid storm is a life-threatening condition due to the acute exacerbation of symptoms of hyperthyroidism, such as the following:

  • Fever

  • Tremors

  • Agitation

  • Altered mental status (eg, coma)

  • Pronounced cardiovascular symptoms (eg, heart failure, tachyarrhythmias including atrial fibrillation)

  • Nausea, vomiting, and/or diarrhea

Thyroid storm can be triggered by stress, such as preeclampsia or induction of labor, especially in patients with poorly controlled hyperthyroidism.

The precipitating condition should be identified and treated. General management includes the intravenous administration of fluids, cardiovascular monitoring, and implementation of cooling measures. PTU is the ATD of choice because it blocks peripheral conversion of T4 to T3. Iodide is given 1-3 hours after the ATD to inhibit the release of thyroid hormones. Dexamethasone is also given to block peripheral conversion of T4 to T3 and to prevent adrenal insufficiency. Propranolol provides beta-blockade and controls the patient's heart rate.

Aggressive thyroid hormone replacement and supportive care are the cornerstones of managing myxedema.

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Deterrence/Prevention

The benefits of universal screening for thyroid disease in pregnancy has not been justified. However, women with the following indicators of high risk should be screened:

  • Personal history of thyroid disease

  • Family history of thyroid disease

  • Goiter

  • Positive thyroid antibodies

  • Symptoms or clinical signs suggestive of thyroid disease (eg, anemia, elevated cholesterol level, hyponatremia)

  • Pregestational diabetes

  • Other autoimmune disorders

  • Infertility

  • Previous head and neck irradiation

  • History of miscarriage or preterm birth

Screening for PPT is recommended for postpartum women with type 1 diabetes and for those with positive anti-TPO results. Screening should occur at 3 and 6 months after delivery.

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Complications

Hyperthyroidism

Uncontrolled hyperthyroidism, especially in the second half of pregnancy, can lead to numerous complications.

Maternal complications

  • Miscarriage

  • Infection

  • Preeclampsia

  • Preterm delivery

  • Congestive heart failure

  • Thyroid storm

  • Placental abruption

Fetal and neonatal complications

  • Prematurity

  • Small size for gestational age

  • Intrauterine fetal death

  • Toxemia

  • Fetal or neonatal thyrotoxicosis, including accelerated bone maturation, goiter, and hydrops

Hypothyroidism

Maternal complications of untreated hypothyroidism

  • Microcytic anemia

  • Preeclampsia

  • Placental abruption

  • Postpartum hemorrhage

  • Cardiac dysfunction

  • Miscarriage

Fetal or neonatal complications

  • Prematurity

  • Stillbirth

  • Delayed bone maturation

  • Goiter

  • Hydrops

  • Poor neurologic development

Postpartum thyroiditis

Complications associated with PPT are maternal, and depression is common. Permanent hypothyroidism may occur in as many as 30% of patients. These women are also at high risk for recurrent PPT after subsequent pregnancies.

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Prognosis

The outcome of pregnancies affected by autoimmune thyroid disease depends on the degree of metabolic control. Women with euthyroid disease can expect satisfactory outcomes of their pregnancy. With close follow-up postpartum, medical therapy can be adjusted to ensure a euthyroid state. This helps ensure a good prognosis.

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Patient Education

The importance of compliance with medical therapy should be stressed. The need for frequent laboratory assessment should be discussed. The adverse effects of medical therapy, including the fetal risks, should be outlined.

For excellent patient education resources, visit eMedicineHealth's Thyroid and Metabolism Center. Also, see eMedicineHealth's patient education article Thyroid Problems.

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