Egg Freezing With Hashimoto's Thyroiditis: 7 Things to Know and Ask Your Doctor

Have Hashimoto's and planning egg freezing? Here are 7 things to know about how your thyroid condition interacts with the process — and the conversations your clinic may not start.

She has Hashimoto's thyroiditis and wants to freeze her eggs. She is asking: higher OHSS risk? How will she feel after? Will it change her TSH? She is asking because nobody in her care has connected these two conditions proactively.

They should have. Here is what that conversation should include.

Egg freezing with Hashimoto's thyroiditis involves specific medical considerations that most fertility clinics do not raise unless you know to ask for them.

7 Things to Know

1. Your TSH must be optimised before starting an egg freezing cycle

Thyroid function directly affects reproductive outcomes. A TSH above 2.5 mIU/L is associated with reduced implantation rates and increased miscarriage risk in IVF populations — and the same principle applies to egg quality during stimulation. Most reproductive endocrinologists recommend TSH below 2.5, ideally below 2.0, before starting fertility treatment.

What to do: Get a current TSH test before your fertility consultation. If your TSH is above 2.5, discuss dose adjustment with your GP or endocrinologist before starting a cycle. Do not begin stimulation with a TSH that is not optimised.

2. Stimulation can temporarily raise TSH by increasing thyroid-binding globulin

High oestrogen during stimulation increases thyroid-binding globulin (TBG), which reduces free thyroid hormone availability and can cause TSH to rise. For women on thyroxine replacement, this may require a temporary dose increase during the cycle. For Hashimoto's patients who are borderline compensated, this shift can push TSH above optimal range during the most critical part of stimulation.

What to do: Tell your fertility clinic and your GP that you have Hashimoto's and want thyroid function monitored during stimulation. Ask whether a prophylactic dose increase during the cycle is appropriate for your specific baseline TSH.

3. Hashimoto's does not directly increase OHSS risk — but atypical stimulation response in autoimmune patients is worth monitoring

OHSS risk is primarily driven by AMH, AFC, young age, and low body weight — not by autoimmune thyroid status. However, some women with autoimmune conditions show less predictable stimulation responses. This is not a reason to avoid egg freezing — it is a reason for more attentive monitoring.

What to do: Ask your RE: 'Do you see any different stimulation patterns in patients with autoimmune thyroid conditions? Is there anything in my monitoring you will pay particular attention to given my Hashimoto's?'

4. Elevated TPO antibodies may be relevant to future embryo transfer — know your antibody status now

Thyroid peroxidase (TPO) antibodies — elevated in most Hashimoto's patients — have been associated with increased miscarriage risk even in women with normal TSH. This is more directly relevant to embryo transfer and pregnancy than to the egg freezing itself. But if you are freezing eggs to use later, knowing your antibody status now is useful planning information.

What to do: Ask your GP for your TPO antibody levels if you do not already know them. If significantly elevated, ask your RE about management strategies at the embryo transfer stage — even if that stage is years away.

5. Post-cycle thyroid fluctuations are possible — check TSH 6–8 weeks after retrieval

The sudden oestrogen drop after retrieval can affect thyroid function in the weeks following the cycle. Some women with Hashimoto's notice increased fatigue, mood changes, or hair changes in the 4–8 weeks post-retrieval that may reflect a temporary thyroid response rather than the ovarian recovery alone.

What to do: Book a TSH test 6–8 weeks after retrieval. Share the result with both your RE and your GP or endocrinologist. If there is a meaningful change from your pre-cycle baseline, discuss whether your thyroxine dose needs adjustment.

6. Post-retrieval fatigue may be more pronounced with Hashimoto's than average

Post-retrieval fatigue is common for all women. For women with Hashimoto's — who often carry a higher baseline fatigue burden — the post-retrieval period can be more significant and longer-lasting. This is physiological, not a sign that the cycle has worsened the underlying condition.

What to do: Plan for a more conservative recovery timeline after retrieval — three to four weeks of reduced obligation rather than the standard one to two. Monitor your energy levels relative to your Hashimoto's baseline.

7. Your fertility clinic and your endocrinologist need to communicate directly — not just through you

Women with Hashimoto's navigating egg freezing are managing two specialties that do not routinely communicate. The fertility clinic manages the cycle. The GP or endocrinologist manages the thyroid condition. The overlap between these two — TSH monitoring and thyroxine dosing during stimulation — requires active coordination, not just a patient relaying information between them.

What to do: Before your cycle starts, ask both your fertility clinic and your GP or endocrinologist to note in your records that you are planning egg freezing. Ask: 'Is there a direct communication mechanism for thyroid monitoring during the cycle?' If not, create one yourself — in writing.