How Does Thyroid Cancer Impact Fertility?
- Most women and men with thyroid cancer of reproductive age remain fully capable of conceiving or fathering a child once their treatments are complete and their hormone levels are stable.
- Therapies such as radioactive iodine do require a waiting period for pregnancy — often 6 to 12 months for women and around 3 months for men — but it generally does not reduce your underlying fertility in the long run.
- Keeping thyroid stimulating hormone (TSH) in a healthy range is essential for fertility, miscarriage risk reduction, and overall well-being, especially if you’re on levothyroxine after a total thyroidectomy (removal of the thyroid).
- Patients who have a higher risk of fertility being impacted should speak to their medical team about egg freezing or sperm banking.
Dr. Mara Roth, an endocrinologist and director of endocrine tumor program at the Fred Hutchinson Cancer Center, tells SurvivorNet that fertility concerns are common among those diagnosed with thyroid cancer as patients are often diagnosed as younger adults.
Read MoreHow Treatment Affects Fertility
Thyroid hormones, produced by a small gland at the front of your neck, help govern your metabolism and influence reproductive function. Even when thyroid cancer is highly treatable, you might be concerned about:- Whether surgical removal of the thyroid (thyroidectomy) affects pregnancy
- How radioactive iodine therapy might delay or complicate fertility plans
- Possible hormone fluctuations that could interfere with conceiving
- The emotional toll of navigating cancer while also thinking about parenthood
Given how common these concerns are, some specialists start discussing fertility and family-planning goals right away, even before treatment begins. This approach ensures that you and your healthcare team can make informed, personalized decisions aligned with your life plans.
“It’s important to realize that these are concerns patients may have. In particular, patients often worry about what’s the impact of radioactive iodine on the need for fertility planning. And what’s very helpful is that there are some really nice studies that show that the ability to get pregnant, to conceive, is no different before or after thyroidectomy and before or after radioactive iodine,” Dr. Roth explains.
Fertility Concerns and Goals
After a thyroid cancer diagnosis, your endocrinologist or oncologist may ask about:
- Your Current Relationship or Family Goals: Even if you’re not in a relationship or not actively planning children, it’s wise to think ahead.
- Age and Hormonal Status: A 38-year-old person may need a different approach than someone who is 25, particularly if there is a 6- to 12-month recommended waiting period for pregnancy.
“In women, it’s particularly important because I think about their age in relation to the timing of when they present,” Dr. Roth explains.
“For example, if a woman presents with a new diagnosis of thyroid cancer at 38 and she was planning to get pregnant at that time, when we give radioactive iodine, we recommend that they wait at least 6 to 12 months after radioactive iodine therapy before conceiving. So, in somebody who’s in their 35 to 40 age range, this is a really important conversation to say: what are the risks or benefits of deferring radioactive iodine, even if it’s recommended to allow a patient to make their fertility goals and to have the family planning and the timing they want?”
If you’ve already had hormonal imbalances or reproductive challenges, that may also influence planning.
It’s perfectly normal for these conversations to feel overwhelming at first. Remember that your medical team is there to guide you every step of the way.
Impact of Treatment on Pregnancy
Surgical Removal of the Thyroid (Thyroidectomy)
A thyroidectomy can be total (removing the entire gland) or partial (removing just one lobe). Usually, needing this operation does not prevent you from becoming pregnant later.
Key points to keep in mind:
- Replacement Hormones: If your entire thyroid is removed, you’ll need daily levothyroxine (synthetic thyroid hormone) to keep levels steady. Experts emphasize that being on thyroid medication alone does not impair your ability to conceive or have a healthy pregnancy, as long as the dosage is correct and your TSH remains in a safe range.
- TSH Targets: If your body is receiving too much thyroid hormone (making you slightly hyperthyroid), studies suggest it could increase the risk of miscarriage in the first trimester. For this reason, your doctor will aim to keep your TSH within a target range that supports both fertility and healthy pregnancy outcomes.
Radioactive Iodine (RAI) Therapy
RAI therapy may be recommended for papillary or follicular thyroid cancer, typically after surgery. The radioactive iodine helps destroy any leftover thyroid tissue or stray cancer cells. Though RAI therapy itself doesn’t appear to reduce long-term fertility, it does require a waiting period before pregnancy:
For women, many specialists suggest waiting 6 to 12 months after RAI before trying to conceive. This allows enough time for your body to clear the radioactive particles and helps ensure your thyroid hormone levels are stabilized.
Men are typically advised to wait 3 months after RAI before trying to father a child, since sperm production recovers more quickly than egg (oocyte) cycles.
“With men, it’s much less challenging. We do recommend, after radioactive iodine, that they not help conceive a child for three months after radioactive iodine therapy, but it’s not that six to 12 month time period that it is for women,” Dr. Roth explains.
This difference can be critical if you’re in your late 30s and hoping to conceive soon. In such cases, your doctor might discuss whether it’s beneficial to delay RAI if your specific thyroid cancer scenario allows it. Every case is unique, and you should have a thorough talk with your oncologist or endocrinologist about balancing cancer treatment with fertility goals.
Other Treatments
- External Beam Radiation (EBRT): This approach, where a beam of radiation from outside the body targets thyroid cells, can affect fertility more if the radiation field is near reproductive organs, but neck-focused EBRT typically poses minimal direct risk to fertility.
- Chemotherapy/Targeted Therapies: While these are not usually standard for most thyroid cancers, they can be necessary for advanced or aggressive forms. Some of these drugs may impact egg and sperm quality, making it wise to discuss fertility preservation strategies (such as sperm banking or egg freezing) if there’s a risk your treatment could harm reproductive cells.
Timing After Radioactive Iodine Therapy
Since the guidelines indicate waiting 6 to 12 months for women to conceive after RAI, timing can be especially important if you’re in your mid- to late-30s or if you were planning a pregnancy soon.
This might raise questions such as:
- Is it safe to delay RAI to pursue pregnancy first?
- Are there alternative ways to manage your thyroid cancer so you can conceive earlier?
These decisions often revolve around a risk vs. reward discussion. If your thyroid cancer is aggressive and needs quick treatment, it may be risky to delay RAI. On the other hand, some lower-risk cases might allow postponing certain therapies to align with a patient’s fertility timeline. This is where an in-depth conversation with your oncologist, surgeon, and possibly a fertility specialist becomes critical. They can help lay out how urgent treatment is, and whether a short delay might be safe.
TSH Levels, Hormones, and Safe Conception
“We see patients on thyroid hormone who get pregnant without problems and have very healthy pregnancies all the time. The fact that a patient is on levothyroxine will not impair their ability to get pregnant as long as we have the TSH in the goal [range] where it’s recommended. If patients are on too high a dose of levothyroxine and their TSH is suppressed, that can actually increase the risk of miscarriage in the first trimester,” Dr. Roth explains.
Your TSH (thyroid-stimulating hormone) is produced by the pituitary gland and spurs the thyroid gland (or any remaining thyroid tissue) to create thyroid hormones. After thyroid cancer, many patients take levothyroxine in doses that keep TSH either at normal levels or slightly lower (suppressed), depending on the risk level of their cancer returning.
If you’re hoping to conceive, let your doctor know your plans before you start trying. They can fine-tune your levothyroxine dose to ensure the TSH is in a “baby-friendly” zone, minimizing complications.
“I always tell patients, you’re allowed to call your mother or your parent first when you get pregnant, but you have to call me second. I always get the second phone call because I want them to then get their thyroid labs checked very early on after a positive pregnancy test. And then there are different approaches to this, but I will typically follow a patient’s labs monthly through the pregnancy,” Dr. Roth says.
Quality of Life and Intimacy Issues
Thyroid cancer often involves surgery on the neck, which can leave a scar. Some individuals — especially younger adults — worry about how the scar or weight fluctuations might impact their self-image or intimate relationships. The emotional side of coping with changes to your body can be significant.
Patients sometimes share:
- A sense of feeling “less attractive” due to the scar
- Struggles with weight changes from adjusting to new thyroid hormone levels
- Concerns about looking or feeling different around a partner
Patients on higher doses of levothyroxine to keep TSH levels very low may also experience symptoms similar to hyperthyroidism, which can reduce libido or cause fatigue and mood shifts. This is more common in individuals with higher-risk thyroid cancer whose doctors must keep TSH suppressed. Over time, guidelines have recognized that such stringent TSH suppression isn’t helpful for all cases and can harm life quality. If you sense changes in your sex drive or comfort, mention it to your care team so they can consider adjusting your medication.
A simple conversation with a partner about these changes — be it body image concerns or a decreased sex drive — can help you both manage expectations and find ways to stay close. Therapy, counseling, or support groups may also offer more tools for handling these emotional hurdles.
Practical Steps to Safeguard Fertility
Patients facing a new diagnosis or preparing to undergo thyroid cancer treatment can take some steps to ensure their chances of starting a family in the future remain high.
- Discuss Preservation: If you’re facing aggressive treatments such as certain chemotherapy drugs or repeated radioactive therapies, ask about egg freezing or sperm banking before starting. Even though it’s rarely needed for standard thyroid cancer care, it can be a safety net.
- Stay on Top of Hormone Tests: Regularly scheduled TSH, T3, and T4 checks ensure your medication is in balance.
- Consider a Fertility Specialist: A reproductive endocrinologist can evaluate your ovarian reserve (egg supply) or sperm quality, give advice on timing, and propose interventions if necessary.
- Coordinate Among Specialists: Endocrinologists, oncologists, and fertility doctors can all weigh in on the safest approach to pregnancy after thyroid cancer.
Questions To Ask Your Doctor
- How might my treatment plan impact my fertility?
- How long will I have to put off trying to conceive a child?
- How frequently should we test my hormone levels?
- Should I consider freezing eggs/sperm banking?
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