Thyroid Health and IVF: What You Need to Know

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Assisted reproductive technology (ART), such as in vitro fertilization (IVF), has provided hope for millions of couples experiencing challenges with fertility. However, underlying health conditions, especially those involving the thyroid, can significantly influence the success and safety of these treatments. Given that your thyroid function plays a crucial role in reproductive health, if you’re considering IVF, it’s essential to understand how your thyroid health might impact your journey.

This article explores the relationship between thyroid health and IVF, including how thyroid hormones affect fertility, how IVF can impact your thyroid function, and what prospective parents should consider before embarking on this path.

The thyroid, a small, butterfly-shaped gland in the neck, is vital in regulating numerous bodily functions, including various metabolic processes, energy levels, and body temperature. For both men and women, thyroid hormones are essential for reproductive health and fertility. Thyroid hormones exert a significant influence on egg follicle development, fertilization, and implantation processes. This intimate connection means that even subtle changes in thyroid function can profoundly affect fertility and pregnancy outcomes.

Both overt hypothyroidism and subclinical hypothyroidism can contribute to fertility problems. Research has shown that women with thyroid dysfunction may experience menstrual irregularities, ovulatory disturbances, and difficulties conceiving. In men, thyroid hormones support sperm production and motility. While thyroid disorders are less common in men, imbalances can still affect fertility and reproductive outcomes. In some cases, these issues persist even after thyroid function is restored to normal levels, necessitating the use of assisted reproductive technologies.

In vitro fertilization (IVF) is an assisted reproductive technology used to help people with fertility issues conceive a child. IVF involves a complex series of procedures where eggs are retrieved from a woman’s ovaries and fertilized with sperm in a laboratory setting. The resulting embryos are then transferred into the uterus with the goal of achieving pregnancy.

The IVF process

The IVF process typically involves several steps:

1. Ovarian stimulation: Hormonal medications are administered to stimulate the ovaries to produce multiple mature eggs.
2. Egg retrieval: A minor surgical procedure is performed to remove mature eggs from the ovaries.
3. Sperm retrieval: A sperm sample is collected from the male partner or a donor.
4. Fertilization: The eggs and sperm are combined in a laboratory dish to facilitate fertilization.
5. Embryo culture: The fertilized eggs are monitored for several days as they develop into embryos.
6. Embryo transfer: One or more embryos are placed directly into the uterus.

Reasons for IVF

IVF may be recommended for various reasons, including:

• Infertility issues such as blocked fallopian tubes, endometriosis, or low sperm count
• Advanced maternal age
• Genetic disorders that couples want to avoid passing on to their children
• Unexplained infertility

Success rates and considerations

The success rate of IVF varies depending on factors such as age, underlying fertility issues, and the quality of the embryos. In 2022, almost 92,000 babies were born in the U.S. using IVF techniques.

It’s important to note that IVF can be expensive, with costs potentially reaching $15,000 or more per cycle. Some insurance plans may cover part or all of the treatment, but coverage varies widely.

Still, IVF has revolutionized fertility treatment since its introduction in 1978, offering hope to many couples struggling with infertility. While it’s not guaranteed to work for everyone, it has helped millions worldwide achieve their dream of having a child.

For individuals undergoing IVF, thyroid disorders -- including overt and subclinical hypothyroidism -- can impact the process in multiple ways:

1. Ovulation and egg quality: Hypothyroidism can lead to irregular ovulation and poor-quality eggs, which can affect IVF outcomes. Low thyroid hormone levels can reduce the quality of the follicles (the fluid-filled sacs containing eggs), potentially lowering the number of viable eggs retrieved during IVF.
2. Endometrial thickness and embryo implantation: Adequate thyroid hormone levels are essential for preparing the uterus for embryo implantation. Hypothyroidism may lead to a thinner endometrial lining, making it more challenging for an embryo to implant successfully.
3. Risk of miscarriage: Studies have shown a correlation between thyroid dysfunction and increased risk of miscarriage, particularly in cases of untreated hypothyroidism or autoimmune thyroid conditions like Hashimoto’s thyroiditis.
4. Hormonal interference: IVF involves taking fertility medications that can impact thyroid hormone levels. Some medications stimulate the ovaries to produce multiple eggs, leading to a rise in estrogen levels. This surge in estrogen can lead to an increase in the body’s production of thyroid-binding globulin (TBG), a protein that binds thyroid hormones in the blood. When more TBG is present, free (active) thyroid hormone levels may decrease, potentially leading to or exacerbating hypothyroid symptoms.

Thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3) interact with the body’s other reproductive hormones, including estrogen, progesterone, and follicle-stimulating hormone (FSH). As a result, proper thyroid function is essential for developing healthy eggs and sperm, as well as for embryo implantation and early pregnancy.

Hypothyroidism, or an underactive thyroid, is one of the most common thyroid disorders seen in women of reproductive age. Hashimoto’s thyroiditis, an autoimmune disease, is the most common cause of hypothyroidism in the U.S. When you’re hypothyroid, your thyroid does not produce enough T3 and T4 hormones, which can lead to a range of symptoms such as fatigue, weight gain, and menstrual irregularities—all of which can interfere with fertility.

How hypothyroidism impacts IVF success

Hypothyroidism can negatively affect the success of IVF procedures. Some of the impacts include:

• Poor ovarian response: Hypothyroidism can reduce ovarian sensitivity to stimulation medications, resulting in fewer follicles and lower-quality eggs.
• Increased risk of miscarriage: Women with untreated hypothyroidism have a higher risk of miscarriage, even if they successfully conceive via IVF.
• Placental development issues: Proper thyroid function is crucial for the early development of the placenta, which nourishes the embryo. Hypothyroidism can disrupt this process, potentially leading to pregnancy complications.

Hashimoto’s thyroiditis is an autoimmune disease where the body’s immune system attacks the thyroid gland, leading to chronic inflammation and, over time, hypothyroidism. Hashimoto’s is one of the most common causes of hypothyroidism, particularly in women. Hashimoto’s can impact fertility and IVF outcomes. Women with Hashimoto’s have a higher risk of developing hypothyroidism, especially during the hormonal changes associated with pregnancy or ovarian stimulation for IVF.

Hashimoto’s can affect IVF in several ways:

• Autoimmune interference with implantation: Some studies suggest that autoimmune thyroid conditions like Hashimoto’s may contribute to an increased risk of failed implantation and miscarriage.
• Fluctuating thyroid hormone levels: Hashimoto’s can lead to periods of thyroid hormone fluctuations, which can complicate IVF treatment and may require close monitoring.
• Anti-thyroid antibodies: People with Hashimoto’s often have elevated levels of thyroid antibodies, such as thyroglobulin (TG) and thyroid peroxidase (TPO) antibodies, which can interfere with reproductive success. These antibodies are linked to higher miscarriage rates, even if thyroid hormone levels are within the normal range.

Given the potential impacts of thyroid health on IVF success, addressing thyroid function before starting assisted reproduction is crucial. Here’s what individuals and couples can do to optimize their chances:

Comprehensive thyroid testing

Given the significant impact of thyroid function on fertility and IVF outcomes, a thorough thyroid evaluation, including the following tests, is recommended for all women considering assisted reproduction.

• TSH: The primary screening test for thyroid function is serum TSH.
• Free T4: Levels of free T4 should also be assessed to provide a complete picture of thyroid function.
• Thyroid antibodies: Testing for thyroid antibodies, particularly TPO-Ab, is crucial in identifying women with thyroid autoimmunity. The presence of these antibodies, even in the absence of overt thyroid dysfunction, may influence IVF outcomes and pregnancy progression.

Research suggests that for individuals planning IVF, the ideal TSH level is typically between 1.0 and 2.5 mIU/L, as this range is associated with better pregnancy outcomes. If TSH is outside this range, your healthcare provider may recommend thyroid medication adjustments.

Medication management

For women with overt or subclinical hypothyroidism, if thyroid medication is needed, levothyroxine (synthetic T4) is often the first line of treatment to achieve and maintain TSH levels <2.5 mIU/L before and during IVF treatment. The dose may need to be adjusted during ovarian stimulation to accommodate increased thyroid hormone demands.

Some individuals with thyroid conditions may also benefit from adding T3 to their treatment of hypothyroidism, but this should be discussed with a healthcare provider. Close monitoring is necessary to ensure thyroid levels remain within the target range throughout the IVF process.

Addressing Hashimoto’s

For women with Hashimoto’s, additional interventions, such as anti-inflammatory dietary changes or immune-modulating treatments, may be beneficial. Supplements like selenium have shown promise in supporting thyroid function, especially in autoimmune thyroiditis, but always consult your doctor before starting new supplements.

Managing stress and lifestyle factors

Chronic stress can exacerbate thyroid dysfunction and impact fertility. Stress management techniques, such as meditation, regular exercise, and sufficient sleep, can help support thyroid health and improve overall well-being during IVF.

Maintaining a healthy diet

A balanced diet rich in essential nutrients like iodine, selenium, zinc, and vitamin D can support thyroid function. Working with a nutritionist can help ensure your diet is optimized for thyroid health and fertility.

Studies have suggested that elevated TSH levels (>4.0 mIU/L) may impair fertilization rates and embryo quality. This underscores the importance of optimizing thyroid function before undergoing IVF treatment.

Women with Hashimoto’s have been found to have a significantly increased risk of miscarriage following IVF. In one study, the miscarriage rate was 53% in women with elevated thyroid peroxidase antibodies (TPO-Ab) compared to 23% in those without antibodies.

The impact of thyroid function on obstetric outcomes and live birth rates in IVF patients has been the subject of extensive research. Meta-analyses have shown that thyroid hormone replacement treatment with clinical improvement in thyroid function can increase live birth rates in women with TSH levels >4.0 mIU/L. However, the benefits of treatment in euthyroid women with thyroid autoimmunity are less clear.

Once IVF treatment begins, monitoring thyroid function becomes even more critical, as hormonal fluctuations and fertility medications can impact thyroid hormone levels. Regular thyroid testing, especially TSH and free T4, should be conducted throughout the process.

If IVF results in a successful pregnancy, thyroid hormone levels should continue to be monitored carefully in pregnant women. Pregnancy demands more thyroid hormones to support the developing fetus, and hypothyroid patients may need increased doses of thyroid medication during pregnancy to maintain optimal thyroid levels.

Here are some special considerations to keep in mind related to Hashimoto’s, hypothyroidism, and IVF treatment.

Euthyroid women with autoimmune thyroid disease 

The management of women with Hashimoto’s who still have otherwise normal thyroid function remains controversial. While some studies have shown the benefits of treatment in this group, recent interventional studies have not demonstrated improved live birth rates in euthyroid women with Hashimoto’s undergoing IVF.

Ovarian stimulation and thyroid function

The hormonal changes induced by ovarian stimulation can significantly affect thyroid gland function. Women with thyroid autoimmunity are particularly susceptible to developing hypothyroidism during this process. Close monitoring and proactive management of thyroid function are crucial during ovarian stimulation.

Polycystic ovarian syndrome (PCOS)

Women with polycystic ovarian syndrome have a higher prevalence of thyroid autoimmunity. This association highlights the importance of comprehensive thyroid evaluation in women with PCOS undergoing IVF.

Thyroid function in men

While much of the focus is on thyroid health in pregnant women, it’s important to note that thyroid dysfunction in men can also impact fertility and IVF outcomes. Male partners should also undergo thyroid evaluation as part of a comprehensive fertility workup.

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• Ensure your doctors collaborate: Thyroid management during IVF often requires collaboration between thyroid and fertility specialists. Working with a team of healthcare providers ensures a comprehensive approach to thyroid and reproductive health.
• Be proactive with thyroid testing and treatment: Comprehensive thyroid testing before and during IVF is essential for identifying potential issues and adjusting treatment as needed for an underactive thyroid.
• Optimize thyroid levels for best results: Achieving and maintaining optimal thyroid hormone levels can increase the chances of successful conception, implantation, and a healthy pregnancy.
• Manage autoimmunity carefully: For individuals with autoimmune thyroid conditions like Hashimoto’s, addressing immune system health may be beneficial in improving IVF outcomes.

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Despite extensive research, many questions remain regarding the optimal management of thyroid disorders in the context of IVF. Areas for future investigation include:

• The precise mechanisms by which thyroid autoimmunity affects fertility and IVF outcomes.
• The potential benefits of LT4 treatment in euthyroid women with thyroid autoimmunity.
• The impact of different types of ART procedures (e.g., intracytoplasmic sperm injection) on outcomes in women with thyroid disorders.
• The long-term effects of thyroid management during IVF on maternal and child health.

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Thyroid health plays a crucial role in fertility and the success of assisted reproductive technologies. For those considering IVF, a comprehensive evaluation of thyroid function should be an integral part of the pre-treatment workup. Proper management of thyroid disorders, including careful monitoring and appropriate treatment, can significantly improve IVF outcomes and increase the chances of a successful pregnancy.

While significant progress has been made in understanding the thyroid-fertility connection, many aspects remain to be fully understood. As research continues to evolve, management strategies will likely be refined to provide increasingly personalized care for those seeking assisted reproduction.

Ultimately, the goal is to optimize thyroid function and overall health to create the best conditions for successful conception, healthy pregnancy, and positive long-term outcomes for both mother and child. By addressing thyroid health proactively, you can take an essential step towards realizing the dream of parenthood through assisted reproductive technologies.

Paloma Health can support your thyroid health during an IVF journey with convenient, easy, and affordable at-home thyroid test kits, virtual visits with knowledgeable thyroid practitioners, and a holistic approach to managing your Hashimoto’s and hypothyroidism with medication and lifestyle changes. Consider joining Paloma Health for comprehensive thyroid care and an opportunity to create lasting health and wellness in your life!