When struggling to conceive, many people focus on hormones, egg quality, and sperm health. But could your immune system be impacting your fertility and overall reproductive health?

Your immune system is designed to protect you from invaders—bacteria, viruses, and toxins. But when it becomes imbalanced or overactive, it can misfire, leading to chronic inflammation, implantation failure, and even recurrent miscarriage.

If you’ve been diagnosed with an autoimmune condition or have unexplained infertility, autoimmunity could be playing a role in your fertility challenges. In this post, we’ll explore the connection between your immune system and fertility and share actionable steps to optimise immune health.

The Link Between Immune Health and Fertility

Your immune system and reproductive system are intricately connected. In a healthy pregnancy, the immune system shifts to a more tolerant state, allowing the embryo—half of which contains foreign DNA from the father—to implant and grow.

But if your immune system is overactive or confused, it can mistakenly attack healthy reproductive tissues, disrupt implantation, or increase inflammation, making conception difficult.

Common immune-related fertility challenges include:

• Inflammation & Implantation Failure – Chronic inflammation can interfere with embryo implantation in the uterus.
• Autoimmune Reactions – Conditions like thyroid autoimmunity, antiphospholipid syndrome, and endometriosis are linked to infertility and miscarriage.
• Recurrent Miscarriage – Immune imbalances can lead to pregnancy loss by triggering blood clotting disorders or rejecting the embryo.
• Poor Egg & Sperm Quality – Inflammation from an overactive immune system can damage eggs and sperm, reducing the chances of conception.

But what triggers these immune imbalances in the first place? One major culprit is your gut.

Could a Leaky Gut Be Affecting Your Fertility?

Your gut is home to 70% of your immune system. It acts as a barrier, preventing harmful substances from entering your bloodstream. But when this barrier weakens—a condition known as leaky gut—toxins, undigested food particles, and pathogens can escape into circulation, triggering an immune response and chronic inflammation.

What causes leaky gut?

• Chronic stress
• A diet high in processed foods and sugar
• Food sensitivities (e.g. gluten, dairy, soy)
• Imbalanced gut bacteria (dysbiosis)
• Toxins and environmental chemicals
• Certain medications (e.g. NSAIDs, antibiotics)

When leaky gut persists, the immune system remains in a constant state of alarm, leading to inflammation that can disrupt hormone balance, ovulation, and implantation.

If you experience symptoms like bloating, IBS, skin issues, allergies, or frequent infections, your gut health may be impacting your fertility.

Autoimmunity and Infertility

Autoimmune conditions occur when the immune system mistakenly attacks the body’s own tissues. In the context of fertility, this can mean attacking:

• Eggs or sperm, reducing quality and viability
• The uterus, leading to implantation failure
• Hormones like thyroid or progesterone, affecting cycle regulation
• Blood vessels, increasing miscarriage risk

Common autoimmune-related fertility conditions include:

• Hashimoto’s thyroiditis (linked to unexplained infertility and miscarriage)
• Endometriosis (associated with immune dysfunction and inflammation)
• Antiphospholipid syndrome (APS) (increases clotting risk, linked to miscarriage)
• Coeliac disease (affects nutrient absorption and reproductive health)

The good news? You can take steps to rebalance your immune system and support fertility.

How to Balance Your Immune System for Optimal Fertility

Healing your gut, reducing inflammation, and supporting immune tolerance can dramatically improve your fertility. Here’s how:

Remove Inflammatory Triggers to Support Immune Health

Certain foods can overstimulate the immune system. Consider eliminating:

• Gluten – A major trigger for leaky gut and autoimmunity
• Dairy – May cause inflammation, especially in sensitive individuals
• Soy – Contains anti-nutrients that may disrupt hormones
• Processed foods & refined sugar – Fuel inflammation and gut dysbiosis

Try an elimination diet for 30 days, then slowly reintroduce foods while monitoring symptoms.

Support Gut Health to Support Immune Health and Fertility

A healthy gut promotes immune balance and hormone regulation, in turn supporting fertility. Focus on:

• Fibre: Eat 30+ plant varieties per week to provide fibre to nourish gut bacteria
• Fermented foods: Include kimchi, sauerkraut, kefir, and live yoghurt for probiotics to help support beneficial bacteria such as lactobacillus
• Prebiotics: Feed good bacteria with garlic, onions, leeks, stewed apples and asparagus, these foods contain soluble fibre that helps beneficial bacteria to thrive. These bacteria not only have a significant impact on immune health and fertility but also on overall health.
• Digestive support: Include bitter greens (rocket, kale, watercress) to support bile production, fat digestion and absorption of fat-soluble vitamins. Include zinc-rich foods, such as shellfish and pumpkin seeds, to help repair the gut lining and reduce inflammation.

Reduce Chronic Stress to Support Your Immune System and Fertility

Cortisol (your stress hormone) suppresses fertility and disrupts immune function. To lower stress:

• Practice mindfulness or meditation
• Try acupuncture (proven to support fertility)
• Prioritise sleep (7-9 hours nightly)
• Engage in gentle movement (yoga, walking)

Your daily habits can have a major impact on your your immune system health and fertility. Discover how in How Lifestyle Choices Affect Fertility.

Optimise Key Nutrients for Gut Health, Immune System Health and Fertility

Certain nutrients help regulate the immune system and hormone function, and support fertility:

• Vitamin A: Supports mucosal barrier integrity (helps protect the gut lining). Foods rich in vitamin A include eggs and liver.
• Omega-3s: Essential for reducing inflammation and supporting fertility in general. Oily fish such as salmon, mackerel and sardines are the richest sources of omega-3 fats. Learn more about why oily fish should be part of your fertility diet in Omega-3 Fats for Fertility
• Vitamin C: Supports immune tolerance and fertility (by protecting egg and sperm cells from oxidative stress)—read more in antioxidants for fertility: why oxidative stress matters
• Vitamin D: Critical for immune system regulation. Oily fish, eggs and liver are the richest food sources of vitamin D but make sure you get sensible exposure to sunlight.

My top 10 fertility-boosting foods are rich in all these nutrients. Find out what they are.

Tip: Check your vitamin D levels and supplement if necessary.

Manage Blood Sugar & Insulin Sensitivity to Support Your Immune System and Fertility

High insulin levels drive inflammation and hormone imbalances. To support balanced blood sugar:

• Prioritise protein and healthy fats at every meal
• Reduce refined carbs and sugar
• Eat balanced, whole-food meals

Balanced blood sugar is crucial for hormone regulation, immune system health and fertility. Learn more in our guide on Balancing Blood Sugar for Fertility.

For fertility-friendly meal inspiration, explore our guide to Fertility Abundance Bowls: A Delicious, Nourishing Approach to Mealtimes.

Key Takeaway: Take Charge of Your Immune System Health to Take Charge of Your Fertility

If you’re navigating unexplained infertility, recurrent miscarriage, or implantation failure, it’s worth exploring whether your immune system is playing a role in your fertility struggles.

By reducing inflammation, optimising gut health, and supporting your immune system, you can improve your chances of conception and a healthy pregnancy.

For a deeper dive into how nutrition supports fertility—including gut health, inflammation and the immune system—get your copy of The Fertility Kitchen Cookbook, which explores these topics further and provides comprehensive nutrition and lifestyle support.