Thyroid Challenges That Can Affect Pregnancy Success

pregnancy, thyroid disease, thyroid, fertility, hypothyroidism

Healthy thyroid function is essential to a healthy reproductive system as well as your ability to successfully conceive, flourish through pregnancy, and deliver a healthy baby. Here are 10 thyroid-related challenges that can affect your ability to have a healthy baby.

1. Lack of Ovulation

If you have an undiagnosed or poorly treated thyroid condition, you are at greater risk of having what is known as an “anovulatory cycle,” a cycle when you don’t release an egg. If an egg is not released, conception and pregnancy can’t occur. Keep in mind; you can still be having menstrual periods, even during anovulatory cycles. You can’t, however, become pregnant.

When thyroid conditions are properly diagnosed and treated, the risk for anovulatory cycles may be reduced.

One way to identify anovulatory cycles is through an ovulation predictor kit, which measures a surge of particular hormones that occurs around ovulation. You may also use a manual or electronic fertility monitoring method, including temperature charting, to identify signs that can indicate ovulation.

If your thyroid issues are resolved, keep in mind that there are other potential reasons for anovulatory cycles that you should explore with your physician. These reasons include breastfeeding; perimenopausal changes; adrenal dysfunction; anorexia; ovarian issues, including low egg reserve, or autoimmune attacks on the ovaries; and polycystic ovary syndrome (PCOS), among others.

2. Luteal Phase Defects

If you have undiagnosed, untreated, or insufficiently treated thyroid problems, you are at greater risk of luteal phase defects. Your luteal phase is the second half of your menstrual cycle, after ovulation, and through the start of your next menstrual cycle.

It is during that luteal phase, after your egg is released, that it begins its journey through the fallopian tubes, where it may be fertilized by sperm, beginning the pregnancy. Under normal circumstances, that fertilized egg then travels to the uterus, where it implants in the uterine lining—known as the endometrium—and the pregnancy continues.

The time needed after ovulation—for preparation of the uterine lining, fertilization of the egg, and successful implantation—is approximately 13 to 15 days. If no fertilized egg is implanted, a hormonal process goes into action, triggering the shedding of the uterine lining as your normal menstrual period.

If your luteal phase is too short, however, there is not enough time for the fertilized egg to successfully implant before the hormonal signal to shed the lining. When this occurs, despite successful conception, the fertilized egg can’t implant and instead ends up being expelled along with menstrual blood.

Luteal phase defects can be identified through fertility charting–Taking Charge of Your Fertility author Toni Wechsler has excellent resources to help you learn how to chart fertility signs. In some cases, your physician may test your follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone levels, to help identify luteal phase defects.

Proper thyroid diagnosis and treatment may resolve luteal phase defects in some women. In some women, however, insufficient progesterone may be the culprit. Progesterone is needed to produce a healthy uterine lining. In those cases, supplemental progesterone has helped some women go on to have a healthy pregnancy and baby.

3. Elevated Prolactin Levels/Hyperprolactinemia

Your hypothalamus produces a hormone called thyroid-releasing hormone, or TRH. The job of TRH is to in turn stimulate your pituitary gland to produce thyroid stimulating hormone or TSH. The TSH then stimulates your thyroid gland to produce more thyroid hormone.

When the thyroid is not functioning properly, high levels of TRH may be produced. This excess TRH can, in turn, trigger the pituitary to also release a hormone called prolactin.  Prolactin is a hormone that promotes milk production.

This condition–known as hyperprolactinemia–can have a number of effects on your fertility, including irregular ovulation and anovulatory cycles. It is higher levels of prolactin while breastfeeding that helps prevent some women from becoming pregnant while breastfeeding.

Charting your menstrual cycle and fertility signs–along with a blood test measuring your prolactin level–can help your physician diagnose hyperprolactinemia. If proper thyroid diagnosis and treatment does not resolve the prolactin issue, several drugs–including bromocriptine or cabergoline–are prescribed, and may help lower prolactin levels and restore your cycles and ovulation to normal.

4. Early Perimenopause/Menopause

If you have an autoimmune thyroid condition such as Hashimoto’s disease, research shows that you face a slightly increased risk of having an earlier onset of menopause. In the United States, the average age of menopause–defined as the point when it has been a full year since your last menstrual period–is 51. Perimenopause is defined as the timeframe when hormonal levels shift and decline–sometimes lasting as long as 10 years–prior to menopause. For some women with undiagnosed, untreated, or insufficiently treated thyroid conditions, perimenopause may begin earlier and menopause may take place at a younger age, thereby shortening childbearing years, and causing reduced fertility at an earlier age.

If you are experiencing perimenopausal changes, a full fertility evaluation, including evaluation of ovarian reserve, FSH, LH, and other hormones, can be performed by your physician to assess your fertility status. Based on the findings, your practitioner may make recommendations regarding whether you are a candidate for natural conception or may want to pursue assisted reproduction.

5. Pregnenolone Conversion Issues

Thyroid hormone plays an important role in converting cholesterol into the hormone pregnenolone. Pregnenolone is a precursor hormone that is converted into progesterone, estrogen, testosterone, and DHEA. When you don’t have enough thyroid hormone, you may have deficiencies in these other key hormones. Deficiencies in progesterone and estrogen, in particular, can disrupt the proper functioning of the menstrual cycle and impair your fertility.

Tests for pregnenolone, progesterone, estrogen, testosterone, and DHEA can evaluate deficiencies in these hormones, and if you are trying to conceive and have notable deficiencies, your physician may recommend hormone replacement as a support in your efforts to have a healthy pregnancy.

6. Estrogen and Your Thyroid

The link between estrogen and thyroid function is a complicated one. Estrogen competes with thyroid hormone to attach to thyroid receptor sites throughout your body. When you have an excess of estrogen, it can actually block your thyroid hormone’s ability to move into your cells. Whether you are taking a prescription medication that includes estrogen, or you have an imbalance in estrogen known as estrogen dominance, an excess of estrogen can disrupt your thyroid and hormonal balance and impair your fertility, even while your thyroid blood test levels appear to be normal.

Evaluation of estrogen and progesterone levels can be performed by your physician, and if you have an excess of estrogen, your physician can provide guidance and treatment to return this hormone to balance, to help improve your fertility and chances of a successful pregnancy.

7. Sex Hormone Binding Globulin (SHBG) Imbalance

If you have undiagnosed or insufficiently treated hypothyroidism, you may also have reduced levels of sex hormone binding globulin, known as SHBG. SHBG is a protein that attaches to estrogen. When your SHBG is low, your estrogen levels can become too high. Excessive estrogen, in addition to creating the imbalance just discussed, can also interfere with growth and development of your follicles, and interfere with the FSH and LH surges associated with ovulation. If you have undiagnosed or improperly treated hyperthyroidism, your SHBG may be elevated, which can then lower your progesterone, a situation that can also lead to estrogen dominance.

SHBG can be measured by a blood test, to evaluate whether a deficiency or excess is affecting your fertility.

8. The First Trimester Thyroid Challenge

During pregnancy, a normal thyroid gland enlarges to that it is able to produce more thyroid hormone for both mother and baby. Thyroid hormone is crucial to a developing baby’s neurological and brain development and is most important during the first trimester when your baby is still developing a thyroid gland capable of producing its own hormone. During that first trimester, the baby relies on you for all essential thyroid hormone. After around 12 to 13 weeks, the fetal thyroid gland is developed, and your baby will produce some thyroid hormone, as well as getting thyroid hormone from you, via the placenta. When you are pregnant, the increased demand for thyroid hormones continues until your baby is born.

If your thyroid is impaired in some way–for example, atrophied due to Hashimoto’s disease and unable to enlarge and produce more thyroid hormone–your thyroid may be unable to provide enough hormone for the baby. This results in worsening maternal hypothyroidism, a situation that is associated with an increased risk of miscarriage, stillbirth, and preterm labor.

A key guideline is that ideally, thyroid disease should be diagnosed and properly treated prior to conception. And if you are being treated for hypothyroidism and planning to conceive before you get pregnant, you and your doctor should have a plan to confirm your pregnancy as early as possible, and to increase your dosage of thyroid hormone replacement as soon as the pregnancy is confirmed.

9. The Need for Iodine

Dietary iodine is the key building block for your body’s production of thyroid hormone. As discussed, pregnancy requires the thyroid to increase in size, and increase the output of thyroid hormone to meet the needs of both mother and baby. Research shows that a pregnant woman has a 50 percent increase in her daily iodine requirement, in order to be able to increase thyroid hormone production.

While the majority of women of childbearing age in the United States are not iodine deficient, the percentage that is is on the rise. According to the National Health and Nutrition Examination Survey (NHANES), around 15 percent of women of childbearing age are currently iodine deficient, and some studies have found even higher rates in certain areas of the nation.

Endocrinologists recommend that women supplement with at least 150 mcg of iodine, from preconception through breastfeeding. An easy way to ensure that you are getting enough iodine is to start taking a prenatal vitamin that contains iodine early when you start planning to conceive and continue taking it until you are done breastfeeding.

Integrative physicians often recommend that you have iodine levels tested prior to conception, and address any iodine deficiencies before you try to get pregnant.

An important note: Inexplicably, the majority of prescription prenatal vitamins and many over-the-counter prenatal vitamins do not contain any iodine. You will need to check labels carefully, to ensure that your prenatal vitamin contains iodine.

Also, keep in mind that some prenatal vitamins also contain iron and calcium. If so, you will need to take them at least 3 to 4 hours apart from your thyroid medication, to prevent any interaction with your thyroid medication that reduces absorption and effectiveness.

10. The Thyroid and Assisted Reproduction

If you are pursuing fertility treatments and assisted reproduction (ART), be aware that ART   puts additional strain on your thyroid. Studies have shown that the need for increased thyroid hormone occurs earlier, and is greater, in women undergoing ART, compared to unassisted conception. If you are hypothyroid and on thyroid hormone replacement treatment, a plan to ensure that your thyroid dosage is adjusted as quickly and as aggressively as possible should be discussed in advance with your fertility doctor.

An important note: don’t assume that your fertility doctor will be on top of your thyroid issues. Surprisingly, some fertility doctors and clinics don’t pay much attention to thyroid testing, or management of thyroid disease during pre-conception, ART, or early pregnancy. You will need to make sure that your fertility doctor or clinic is thyroid-savvy, and that they have a plan in place to ensure that your thyroid does not interfere with the success of ART treatments or a healthy pregnancy.

Your Next Steps

One of the best steps you can take is to make sure that your obstetrician-gynecologist, thyroid practitioner–and fertility doctor, if applicable–are knowledgeable about thyroid disease, and will partner with you at every step of the way to ensure optimal thyroid health.

Research has shown that many obstetricians are not particularly savvy about managing pregnancy in thyroid patients. In fact, one survey of obstetrician-gynecologists’ found that only 50 percent of the doctors felt that they had received “adequate” training in managing thyroid disorders during pregnancy. Many endocrinologists are similarly unprepared to manage thyroid disease in their pregnant patients. You may want to investigate having a reproductive endocrinologist on your medical team, as these specialists tend to be more knowledgeable about how the thyroid affects fertility and pregnancy.

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