Hypothyroidism and Reproduction

Hypothyroidism and Fertility

The occurrence of hypothyroidism -the thyroid’s failure to produce adequate amounts of thyroid hormone- among women is somewhat common; studies have suggested that the percentage of American women experiencing some degree of thyroid hormone deficiency may be as high as 10%. While the impact of hypothyroidism can, depending on the extent of the condition, vary widely -from no symptoms to debilitating mental and physical sluggishness-, the effects of this condition on the female reproductive system can be especially burdensome for a woman in her reproductive years.

In some lucky few hypothyroid women, irregular menstrual cycles lead to seeking medical evaluation in turn leading to a timely diagnosis of low thyroid function followed by proper treatment before the onset of any adverse impact. However, more often than not, events do not unfold in this manner. Low thyroid hormone levels can interfere with the proper functioning of the female reproductive system by effecting ovulation. A key aspect of hypothyroidism among women of child-bearing years to be aware of is that not always will the condition manifest with alarming symptoms such as irregular menstruation. In fact, in many cases, despite the lack of regular and frequent ovulation, menses may take place regularly. Hopeful mothers-to-be whose hypothyroidism has gone undiagnosed quite often find themselves seeking medical evaluation and treatment following unsuccessful attempts at conception. Subsequent evaluation and thorough examination then reveals the difficulty to be the result of either highly irregular ovulation or no ovulation at all due to below normal thyroid hormone levels. As displeasing as this scenario seems, there is a positive aspect to it and that is the discovery of the condition before pregnancy was established.

Hypothyroidism and Miscarriage

Following successful conception, as is the case with so much else in nature, the maintenance of a pregnancy is dependent on a host of hormonal events that must take place according to a fixed schedule. The production of progesterone, a hormone with a key role in this process, is among the many factors adversely effected by hypothyroidism. Women with undiagnosed overt low thyroid function (high TSH, low T3, T4 and symptomatic) as well as subclinical hypothyroid (high TSH, normal T3, T4, with or without symptoms) are not only at increased risk of having difficulty conceiving, they are also exposed to a higher risk of experiencing miscarriage. The experience of multiple miscarriages is very often what drives couples to turn to their medical professional for testing and evaluation. The disappointment and hardship that is endured as a result of difficulty conceiving and/or the experience of miscarriage(s) are in and of themselves compelling reasons why women should be screened for thyroid function prior to planning a pregnancy so that proper measures can be taken for not only the prevention of such outcomes but also the promotion of a successful conception and a healthy pregnancy.

Hypothyroidism During Pregnancy

Sever hypothyroidism is rarely encountered during pregnancy since patients with this level of low thyroid function experience difficulty achieving conception in the first place. Patients with mild hypothyroidism on the other hand, may in fact successfully conceive which then increases the likelihood that the condition goes undetected for at least part of their maternity. While hypothyroidism on its own can lead to a variety of serious problems, hypothyroidism during pregnancy places the developing child at risk of problems that are at least equally as serious and often more grave than the effects of hypothyroidism alone, such as severe developmental anomalies. Primary outcomes of undiagnosed/untreated hypothyroidism during pregnancy (both obstetrical and neonatal complications) include:

  • Miscarriage
  • Hypertension
  • Preeclampsia
  • Gestational DM
  • Placenta Abruption
  • Thyroid Storm
  • Cesarean Delivery
  • Congestive Heart Failure
  • Preterm Delivery
  • Respiratory Distress
  • NICU Admission
  • Low Birth Weight
  • High Birth Weight
  • Low IQ
  • Prenatal Death

Hypothyroidism Risk Factors

The risk of developing hypothyroidism is heightened among women who meet one or more of the following criteria:

  • Family history of autoimmune thyroid disease (i.e.; Hashimotoe’s Hypothyroid, Graves’ Disease)
  • Presence of goiter or an enlarged thyroid gland
  • The presence of Signs and symptoms of thyroid dysfunction
  • Personal history of diabetes mellitus type one or other autoimmune disorder
  • History of neck irradiation
  • History of miscarriages
  • History of pre-term deliveries

Screen or not to Screen

If you are a woman of reproductive age with no apparent health issues and you have hopes of starting or expanding your family in the near term, you may be contemplating the question of whether or not to be screened for hypothyroidism. Although this is not done routinely, Dr. Aidun recommends a thorough thyroid evaluation for women planning to achieve pregnancy. Because of the non-specificity of the typical clinical manifestations of the condition, the process of screening for hypothyroidism consists mostly of laboratory testing whereby concentrations of serum hormones and antibodies are measured and evaluated for abnormalities.

For women who are already pregnant, Dr. Aidun recommends screening for thyroid function as early in pregnancy as possible with continued screening every trimester.


In the event of a diagnosis of overt or subclinical hypothyroidism, thyroid replacement therapy is the recommended course of action. Ideally, this treatment should begin prior to becoming pregnant. Thyroid Stimulating Hormone (TSH) levels should be closely monitored once treatment has been initiated so that once the specific “preconception” range is achieved it can be maintained through properly adjusted therapy.

The body’s need for thyroid hormone as well as its ability to metabolize thyroid hormone changes over the course of the different stages of pregnancy. Dr. Aidun, in addition to being an advocate for thorough preconception thyroid evaluation and work up, adheres to a strict set of treatment guidelines based on research and standards taught at the Clinical Endocrinology Dept. at Harvard Medical School whereby treatment is specifically formulated for each stage of the female reproductive cycle and levels of thyroid hormone are monitored frequently and adjustments are made accordingly.

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