Thyroid Health and Fertility: What Your Body’s Trying to Tell You
For many people, the path to parenthood isn’t always linear. If you’ve been trying to conceive, struggling with irregular periods, or have a history of miscarriage or hormone imbalance, your thyroid might be part of the story.
It’s an often-overlooked piece of the reproductive health picture—but an important one.
Why The Thyroid Matters for Fertility
The thyroid is a small gland at the base of your neck. It produces hormones that regulate metabolism, but its role doesn’t end there. Thyroid hormones also influence menstrual cycles, ovulation, egg quality, and the body’s ability to prepare for and sustain pregnancy.
Even mild thyroid dysfunction, often missed in basic blood tests, can influence hormone balance and reproductive function.
How Hypothyroidism Affects Female Fertility
An underactive thyroid (hypothyroidism) can affect fertility in several interconnected ways:
Increases prolactin, which can suppress ovulation
Impairs insulin sensitivity, contributing to PCOS
Slows oestrogen metabolism, leading to excess oestrogen
Lowers progesterone, crucial for cycle regulation and pregnancy maintenance
Affects FSH and LH levels, impairing follicle development
Can lead to anovulatory cycles and irregular menstruation
Reduces basal body temperature, often seen in those struggling to conceive
Increases the risk of miscarriage and implantation issues
Associated with lower AMH levels and diminished ovarian reserve
Research also links hypothyroidism with complications like pre-eclampsia, caesarean delivery, and postpartum haemorrhage.
Hyperthyroidism and Reproductive Health
Hyperthyroidism, while less common, also impacts fertility:
Shortens menstrual cycles and can cause light or missed periods
Disrupts the luteal phase and may impair ovulation
Affects cervical mucus, which can reduce sperm motility
May cause ovarian changes and alter hormone balance
In autoimmune cases (like Graves’ disease), thyroid antibodies can interfere with ovarian function.
The Role Thyroid Autoimmunity
Thyroid autoimmunity is increasingly recognised as a contributor to unexplained infertility. Even with normal hormone levels, the presence of thyroid antibodies, particularly TPO and TG, can affect egg quality and early pregnancy outcomes.
Linked to higher miscarriage rates
May contribute to Premature Ovarian Insufficiency (POI)
Found more frequently in women with PCOS
Antibodies may be present in follicular fluid, affecting folliculogenesis.
Male Fertility and Thyroid Health
Though hypothyroidism is less common in men, it can still influence sperm quality, including motility and morphology. Iodine deficiency in particular has been associated with reduced motile sperm count and lower fertility outcomes.
Iodine and Nutrients for Thyroid Support
If you’ve ever wondered how your diet might be influencing your cycle, energy levels, or even your chances of conceiving, this is where the conversation gets interesting.
The thyroid doesn’t function in isolation. It relies on a steady supply of nutrients to keep hormone production humming, and some of the most important players are also vital for reproductive health.
Take iodine, for example. It’s the raw material for thyroid hormone production, but it also supports the ovaries and stabilises oestrogen receptors—key for timely ovulation. Yet, many people aren’t hitting their daily iodine needs, especially if they avoid iodised salt, dairy, or seafood.
Other must-haves include:
Selenium – helps regulate immune responses and reduce thyroid antibodies
Zinc – essential for egg development and hormone balance
Vitamin D – modulates autoimmunity and supports ovarian function
Iron – needed to convert T4 into active T3, and support healthy cycles
These nutrients don’t just support your thyroid; they influence your whole endocrine network. For those managing PCOS, endometriosis, or irregular cycles, replenishing these foundations can be a game-changer.
If you’ve never had your levels tested, or you’re unsure where to begin, this is something we can explore in a consultation together.
What to Test and Why It Matters
If you’re trying to conceive or working through hormone symptoms, a comprehensive thyroid panel is key. This includes:
TSH
Free T4 and Free T3
Reverse T3
Anti-TPO and Anti-TG antibodies
TRAb (if hyperthyroid symptoms are present)
Iodine (serum or urinary)
Basal body temperature charting
We’re not just looking for disease—we’re looking for optimal function, especially during preconception care.
How to Take The Next Step
If something doesn’t feel right—whether it’s your cycle, your energy, or your path to conception—it may be time to look deeper.
Book a naturopathic consultation focused on hormone and fertility support, or take the Hormone Assessment Tool, created to help you better understand where your body is at and what steps to take next.
DISCLAIMER
This content is not intended as medical advice and should not be used to diagnose, treat or prevent any disease or health illness. Please consult a qualified healthcare professional before acting on any information presented here.
Further reading:
Latest articles
