How to Choose the Right Functional Tests for Fertility and Hormone Health
- Rachael Robinson
- Oct 17
- 5 min read
Table of Contents
Key Takeaways
Functional testing gives deep insight into your health but must be chosen carefully.
There’s no one-size-fits-all approach — the right test depends on your symptoms, goals, and timeline.
Gut, hormone, nutrient, seminal and vaginal microbiome testing are some of the most valuable tools in fertility care.
I’m often asked which tests are most important or where to start when exploring functional testing for fertility or hormone health. It’s a great question, and one without a simple answer. Functional testing can be an investment, so it’s important to make choices that truly support your goals.
The truth is, there isn’t one perfect starting point for everyone. Each person’s health story, symptoms, and fertility timeline are unique. My approach is always personalised, guided by your specific needs and the areas that seem most likely to uncover the root causes of what’s going on.
What Is Functional Testing?
Functional testing looks at how your body is functioning at a deeper level. It helps us to uncover imbalances that might not appear on standard medical tests: things like nutrient deficiencies, inflammation, hormone imbalances, or gut health issues that can all affect fertility and wellbeing.
These tests can provide a clear picture of what’s happening inside your body so that your nutrition and lifestyle plan can be more targeted and effective.
Why the Right Test Depends on You
When clients ask, “Which test should I start with?” my answer is always, “It depends.” That can sound frustrating, but it’s the truth.
Someone struggling with digestive symptoms might benefit most from a stool or SIBO test. Someone experiencing irregular cycles or low energy might start with hormone testing. If a client is preparing for IVF, a vaginal microbiome or seminal microbiome test might be a priority to optimise implantation success.
The right choice depends on symptoms, health history, and what stage you’re at on your fertility journey.
1. Gut Health Testing: Stool and SIBO testing
Why it matters
The gut is where everything begins. It affects nutrient absorption, hormone balance, inflammation, and even immune health — all of which are crucial for fertility.
When your gut isn’t functioning well, it can contribute to symptoms like bloating, fatigue, food sensitivities, poor nutrient absorption, recirculation of hormones and skin problems. It can also impact how your body metabolises hormones like oestrogen. If someone does not have a daily bowel movement then gut health is the area that we have to start with.
Types of tests
I typically assess gut health using two different tests: a stool test and a SIBO test. The stool test requires a stool sample and provides insight into how well the large intestine is functioning. The SIBO test, on the other hand, is a breath test used to understand what’s happening in the small intestine and whether there’s an overgrowth of methane or hydrogen-producing bacteria.
What it shows
Comprehensive gut testing looks at digestion, microbiome balance, inflammation, and markers of infection or overgrowth. It can reveal imbalances in beneficial bacteria or issues like yeast or parasites that might be affecting your overall health.
Example from clinic
I recently worked with a client who was experiencing irregular bowel movements and bloating. Her stool test showed very low beneficial bacteria and signs of inflammation, and her SIBO showed that she had elevated levels of methane producing bacteria. Once we addressed this through nutrition and targeted supplementation, her digestion significantly improved and so did her hormone fluctuations throughout the month.
2. Hormone and Thyroid Testing
Why it matters
Hormones are powerful messengers that influence everything from mood to ovulation. Small imbalances can have big effects on fertility and menstrual health.
Testing reproductive and thyroid hormones gives valuable insight into ovulation, luteal phase health, and adrenal function. This information can help guide supplement choices, nutrition, and timing for fertility treatments.
Common markers
Functional hormone panels often measure oestrogen, progesterone, testosterone, DHEA, cortisol, thyroid hormones (TSH, T4, T3), and sometimes AMH or FSH for ovarian reserve.
Client example
One client was experiencing severe PMS and irregular cycles. Her hormone test showed low progesterone and high cortisol. Supporting her stress response through nutrition and lifestyle changes helped balance her hormones within three months.
3. Nutrient and Micronutrient Testing
Why it matters
Even a healthy diet can miss key nutrients needed for fertility and energy. Functional testing for vitamins, minerals, and antioxidants provides clarity on what your body really needs.
What it shows
These tests can identify deficiencies in nutrients like B12, vitamin D, zinc, iron, or omega-3 fatty acids — all of which support hormone balance, egg quality, and a healthy uterine environment.
In practice
I often recommend this test for clients as a baseline. It can pick up nutrient deficiencies and sub optimal levels which can directly impact fertility. Iron is something that is often sub optimal, or not well stored and iron is directly involved in ovulation and implantation.
Knowing exactly which nutrients are low allows us to supplement more effectively rather than guessing.
4. Vaginal/Seminal Microbiome Testing
Why it matters
This test is especially important for anyone preparing for IVF or struggling with implantation or recurrent miscarriage. The vaginal microbiome plays a major role in reproductive health.
I see a number of women in my clinic who are completely asymptomatic but end up having infections such as bacterial vaginosis, or unwanted pathogens such as Ureaplasma - both of which can impact implantation, inflammation and miscarriage risk.
A healthy vaginal microbiome should be dominated by Lactobacillus species, which help keep the environment slightly acidic and protective. If the balance shifts, it can increase the risk of inflammation, infection, or implantation difficulties.
I will often run a seminal microbiome test for males as well. Many bacteria pass between couples.
What it shows
Vaginal microbiome testing identifies the types and balance of bacteria in the vaginal environment. It helps pinpoint whether there’s an overgrowth of less helpful bacteria or if beneficial strains are too low.
Client story
One client had two failed IVF transfers. Her vaginal microbiome test showed low Lactobacillus and high Gardnerella levels. With antibiotics (prescribed by her gynaecologist), biofilm disruptors, herbs, targeted probiotics and nutrition changes we cleared out the unwanted bacteria, repopulated the helpful and her next transfer was successful.
5. Inflammation and Metabolic Testing
Why it matters
Chronic inflammation or metabolic imbalance can interfere with hormone health and egg quality. For clients with endometriosis, PCOS, or weight management goals, testing inflammatory and insulin markers provides vital insight.
Markers such as CRP, fasting insulin, and HbA1c can help guide dietary adjustments and supplement support. Balancing blood sugar and reducing inflammation can significantly improve fertility outcomes.
Putting It All Together
Choosing the right functional tests isn’t about ticking boxes. It’s about asking, “What’s most likely to give us useful answers right now?”
I often start with one or two key areas rather than testing everything at once. This helps manage costs while ensuring we gather the most relevant information. As results come in, we can layer in additional testing if needed.
The goal is always to create a clear, evidence-based plan that supports your fertility and hormone health in the most efficient way possible.
Conclusion
Functional testing can be an incredible tool for understanding your body on a deeper level. By choosing the right tests — whether that’s gut health, hormone panels, nutrient analysis, or vaginal microbiome testing — you can move from guessing to knowing.
When you understand what’s going on inside your body, you can take more confident steps toward your health and fertility goals.
What Next?
If you’re interested in which functional tests might be most useful for your fertility or hormone journey, book a consultation. We’ll review your symptoms, goals, and timeline to create a plan that’s personalised, practical, and evidence-based.
Arrange a 1:1 session with me to create a personalised, practical strategy for the months ahead. You don’t need to figure it out alone—I'm here to support you every step of the way.
[Please do reach out via the contact form and we can discuss how best to support you]
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