Improving Fertility Naturally: A Root-Cause Approach

When women come to me wanting to improve their fertility, the conversation rarely starts where they expect. We don't begin with ovulation predictor kits or timing intercourse. We start much further upstream — with the state of their hormonal health, the quality of their nutrition, and the underlying patterns that have been playing out in their cycles for months or years.

Fertility isn't an isolated event. It's the downstream expression of your hormonal ecosystem. When that ecosystem is functioning well — when you're ovulating consistently, producing adequate progesterone, and your thyroid, blood sugar, and stress response are all working in concert — conception becomes far more likely. When it isn't, even "unexplained infertility" often has identifiable root causes.

This article is a comprehensive guide to the root-cause approach to fertility — what to investigate, what to address, and how to build the strongest possible hormonal foundation before trying to conceive.

Fertility Starts with Ovulation

Ovulation is not just important for fertility — it is fertility. Without ovulation, there is no egg available for fertilisation, no corpus luteum to produce progesterone, and no biological signal that the cycle is functioning reproductively. Everything hinges on this single event.

Understanding the sequence of ovulation helps clarify where things can go wrong. In the mid-follicular phase, rising FSH (follicle-stimulating hormone) recruits a cohort of follicles and stimulates one dominant follicle to mature. As that follicle grows, it produces increasing amounts of estrogen. This estrogen rise reaches a threshold that triggers a sharp, brief LH (luteinising hormone) surge from the pituitary — typically 24–36 hours before ovulation. The LH surge is the trigger that causes the mature follicle to rupture and release the egg.

After ovulation, the ruptured follicle transforms into the corpus luteum, which produces progesterone — the hormone that prepares the uterine lining for implantation and supports early pregnancy. If conception does not occur, the corpus luteum degenerates, progesterone drops, and menstruation begins. If conception does occur, the developing embryo produces hCG (human chorionic gonadotropin), which signals the corpus luteum to keep producing progesterone until the placenta takes over at around 10–12 weeks.

The fertile window is narrow: the egg survives for 12–24 hours after ovulation, but sperm can survive in the reproductive tract for up to 5 days. Intercourse in the 3–5 days before ovulation and on the day of ovulation itself covers the fertile window. This is why accurate ovulation tracking matters far more than tracking your period date.

The Key Hormones for Fertility

Fertility requires a precise hormonal sequence, and impairment at any stage can affect the outcome. Here are the key players and what each one does:

FSH (Follicle-Stimulating Hormone)

FSH is produced by the pituitary gland and is responsible for recruiting and stimulating follicle development in the ovaries. Elevated day 3 FSH is a marker of diminished ovarian reserve — the pituitary is having to "shout louder" to stimulate follicles. Normal day 3 FSH is below 10 mIU/mL; levels above this suggest reduced ovarian response.

LH (Luteinising Hormone)

LH is the trigger for ovulation. The mid-cycle LH surge — detectable with OPKs — is the signal that ovulation is approximately 24–36 hours away. In PMOS, LH is chronically elevated (typically with a high LH:FSH ratio), which disrupts normal follicle development and prevents ovulation. In hypothalamic amenorrhoea (HA), both FSH and LH are suppressed due to insufficient caloric intake or chronic stress.

Estrogen

Estradiol, produced by the growing follicle, drives follicle development and prepares the uterine lining for implantation. Adequate estrogen is needed for the LH surge to be triggered. In women with hypothalamic amenorrhoea or low body weight, insufficient estrogen means the follicular phase fails to complete and ovulation doesn't occur.

Progesterone

Progesterone is produced by the corpus luteum after ovulation and is the essential hormone of the luteal phase. It thickens the uterine lining for implantation, inhibits further ovulation, and supports early pregnancy. Low progesterone — evidenced by mid-luteal levels below 10 ng/mL or a luteal phase shorter than 10 days — is one of the most common and underdiagnosed causes of implantation failure and early miscarriage.

Thyroid Hormones

Thyroid hormones are essential for virtually every step of reproduction: follicle development, the LH surge, implantation, early embryonic cell division, and neural development in the first trimester. Even subclinical hypothyroidism (TSH above 2.5 mIU/L in a fertility context) is associated with reduced conception rates and increased miscarriage risk. Thyroid antibodies (anti-TPO, anti-TG) can disrupt fertility independently of TSH. A comprehensive thyroid panel is a non-negotiable part of preconception assessment.

AMH (Anti-Müllerian Hormone)

AMH is produced by small antral follicles in the ovaries and is the best available marker of ovarian reserve — the quantity of eggs remaining. AMH declines with age but can also be suppressed by low vitamin D, certain autoimmune conditions, and following oral contraceptive use (it returns to normal after cessation). Low AMH does not mean conception is impossible, but it does inform the timeline and approach.

Common Fertility Blockers

Irregular or absent ovulation

The most common cause is PMOS (formerly Polycystic Ovary Syndrome), which disrupts follicle development through elevated LH and insulin resistance driving androgen excess. PMOS is the leading cause of ovulatory infertility. Hypothalamic amenorrhoea (HA) is the second most common — driven by energy deficit, over-exercise, or chronic psychological stress. Both are highly responsive to root-cause interventions. Thyroid dysfunction (both hypothyroidism and hyperthyroidism) also disrupts ovulation and should always be ruled out in women with cycle irregularity.

Low progesterone and short luteal phase

A luteal phase shorter than 10 days does not provide adequate time for implantation. Low progesterone in the mid-luteal phase (below 10 ng/mL) means the uterine lining is not adequately prepared to receive and sustain a fertilised egg. This pattern — sometimes called luteal phase defect — is associated with irregular spotting before the period, very short cycles, and recurrent early miscarriage. Supporting progesterone production through ovulation support, stress reduction, and targeted nutrition and supplementation is often highly effective.

Poor egg quality

Egg quality refers to the chromosomal and mitochondrial integrity of the egg — its ability to be fertilised, develop into a healthy embryo, and implant successfully. Egg quality declines with age (most significantly after 35), but is also significantly affected by oxidative stress, nutrient deficiencies, environmental toxin exposure, and mitochondrial dysfunction. Importantly, because the final maturation of eggs takes approximately 90 days, the nutritional and environmental conditions of the 3 months before ovulation directly determine egg quality.

Endometriosis

Endometriosis — in which endometrial-like tissue grows outside the uterus — affects fertility through multiple mechanisms: inflammation in the pelvic cavity impairs egg quality and the fertilisation environment; adhesions can block the fallopian tubes; and the inflammatory cytokines produced can reduce implantation success. Even in women with mild endometriosis, the chronic inflammatory state meaningfully impairs fertility. Anti-inflammatory nutrition, immune modulation, and addressing estrogen dominance are all important parts of a root-cause approach.

Uterine fibroids

Fibroids affect fertility depending on their location. Submucosal fibroids (growing into the uterine cavity) have the most significant impact on implantation and are associated with increased miscarriage risk. Intramural fibroids (within the uterine wall) may affect fertility if they distort the cavity. Subserosal fibroids (growing outward) generally have the least impact. Fibroids are estrogen-dependent; addressing estrogen dominance is an important part of managing their growth.

Male factor — the often-overlooked half

Male factor infertility accounts for approximately 40–50% of fertility challenges — yet it is frequently the last thing investigated. Sperm parameters (count, motility, morphology, and DNA fragmentation) are all modifiable through root-cause interventions: antioxidant nutrition, CoQ10, zinc, vitamin C and E, omega-3, reducing alcohol and heat exposure, and managing stress. A semen analysis should always happen in parallel with female investigation — not as a last resort.

Preconception Nutrition

The 3–6 months before conception are among the most nutritionally consequential of a woman's life. Egg maturation (folliculogenesis) takes approximately 90 days, meaning the nutritional environment during this window directly determines the quality of the eggs that will be available for fertilisation. At the same time, the early weeks of pregnancy — before most women know they are pregnant — are critical for neural tube closure, organ formation, and implantation. Building nutritional reserves before conception is not optional; it is the foundation of fertility.

Methylated folate

Folate (as methylated 5-MTHF, not synthetic folic acid) is the single most important preconception nutrient. It is required for DNA synthesis and repair, neural tube development, and methylation — the biochemical process that regulates gene expression across every cell in the developing embryo. Neural tube closure occurs in the first 28 days of pregnancy — before most women know they are pregnant — making preconception supplementation essential. 400–800 mcg of methylated folate daily is the standard recommendation; women with the MTHFR gene variant may need higher doses under practitioner guidance.

CoQ10 for egg quality

Eggs contain more mitochondria than virtually any other cell type — because fertilisation, cell division, and early embryonic development require enormous amounts of energy. CoQ10 (as ubiquinol, the active, reduced form) is the critical cofactor for mitochondrial energy production. Supplementing with 200–600 mg/day of ubiquinol for at least 3 months before conception is one of the most evidence-supported interventions for improving egg quality, particularly in women over 35 or those with unexplained fertility challenges.

Omega-3 fatty acids

DHA (docosahexaenoic acid) is a structural component of cell membranes and is essential for the developing brain and nervous system. Omega-3 fatty acids also reduce the inflammatory environment that impairs egg quality, implantation, and early pregnancy. A minimum of 2g/day of combined EPA and DHA from a high-quality, oxidation-tested fish oil (or algal oil for plant-based women) is recommended preconceptionally and throughout pregnancy.

Vitamin D

Vitamin D is a steroid hormone that plays a direct role in follicle development, ovarian reserve (AMH levels are associated with vitamin D status), implantation, and early pregnancy immune regulation. Deficiency — affecting the majority of women living at northern latitudes — is associated with reduced IVF success rates, irregular ovulation, and increased miscarriage risk. Testing vitamin D levels (aim for 40–60 ng/mL) and supplementing appropriately (typically 2000–5000 IU/day) is an important preconception step.

Iron

Iron deficiency — even without clinical anaemia — impairs ovulation. Research has shown that women with higher non-haem iron intake have significantly lower rates of ovulatory infertility. Iron is also critical in early pregnancy for placental development and foetal red blood cell production. Ferritin levels below 30 ng/mL (and ideally closer to 70–100 ng/mL for fertility purposes) are associated with impaired ovulatory function.

Zinc

Zinc is required for follicle development, ovulation, and progesterone production. It is also one of the most important minerals for sperm quality and DNA integrity. Zinc deficiency — common in women eating low amounts of red meat or shellfish — impairs the LH surge and reduces progesterone output from the corpus luteum.

Antioxidants

Oxidative stress is one of the primary drivers of poor egg quality and DNA damage in both eggs and sperm. Vitamin C (500–1000 mg/day) and vitamin E (200–400 IU/day as mixed tocopherols) work synergistically as antioxidants to protect the egg from oxidative damage during maturation. Eating a wide variety of colourful vegetables and fruits provides additional antioxidant diversity.

Lifestyle Factors

Blood sugar regulation

Insulin resistance — driven by a high-sugar, refined carbohydrate diet, chronic stress, and inadequate sleep — is one of the most common metabolic barriers to fertility. In women with PMOS, insulin resistance drives elevated LH and excess androgen production, disrupting follicle development. But even without a PMOS (formerly PCOS) diagnosis, blood sugar dysregulation impairs ovulation, suppresses progesterone, and creates an inflammatory environment that reduces fertility. Eating protein and healthy fats with every meal, prioritising whole food carbohydrates, and managing stress are the foundational strategies.

Stress and the HPA-HPG axis

Chronic psychological or physiological stress activates the HPA (hypothalamic-pituitary-adrenal) axis and suppresses the HPG (hypothalamic-pituitary-gonadal) axis — the hormonal cascade that drives ovulation. Under sufficient stress load, the brain literally prioritises survival over reproduction: GnRH is suppressed, FSH and LH drop, and ovulation either becomes irregular or stops altogether. Supporting the stress response through sleep, nervous system regulation (breathwork, nature, community), realistic exercise loads, and cortisol-lowering adaptogens (with practitioner guidance) is a fertility intervention in itself.

Exercise

Moderate, consistent exercise supports fertility by improving insulin sensitivity, reducing inflammation, and supporting mood and stress resilience. However, excessive exercise — particularly high-intensity training at volume — creates an energy deficit that signals the hypothalamus to suppress GnRH. This is particularly relevant in women with hypothalamic amenorrhoea. The right exercise dose for fertility is one that supports rather than depletes: 3–5 sessions per week of moderate-intensity movement, with adequate recovery and caloric intake to match.

Sleep

Sleep is when the body produces and regulates most of its hormones — including LH, FSH, and melatonin (which has direct antioxidant effects in the follicle). Chronic sleep deprivation disrupts the hormonal rhythms that drive ovulation and elevates cortisol, compounding the stress burden. Seven to nine hours of quality sleep, with consistent sleep and wake times, is a non-negotiable fertility support strategy.

Environmental toxin reduction

Endocrine-disrupting chemicals — including BPA and phthalates from plastics, pesticide residues on food, PFAS from non-stick cookware, and parabens in personal care products — directly disrupt ovarian function, egg quality, and implantation. Switching to glass and stainless steel food storage, choosing organic produce, and transitioning to natural personal care products reduces the total xenoestrogen burden and supports the hormonal environment for fertility.

Alcohol

Even moderate alcohol consumption is associated with reduced fertility. Alcohol impairs liver estrogen metabolism, disrupts sleep architecture, raises cortisol, and depletes B vitamins and zinc — all of which undermine the hormonal conditions needed for conception. During the preconception period and while actively trying to conceive, minimising or eliminating alcohol is a meaningful step.

When to Seek Additional Help

Root-cause hormonal work is powerful — but it's most effective when you also have a clear picture of what is happening hormonally and structurally. Knowing when to investigate is as important as knowing what to do.

When to seek investigation

• •Under 35: after 12 months of regular unprotected intercourse without conception
• •35 and over: after 6 months — and sooner if cycles are irregular, periods are absent, or there is a known underlying condition
• •Immediately: with recurrent miscarriage (two or more losses); known PMOS (formerly PCOS), endometriosis, fibroids, or thyroid condition; or known male factor issues
• •Irregular cycles or absent periods: even before actively trying — addressing the underlying cause of cycle irregularity is the most important preparatory step

Comprehensive preconception lab testing

A meaningful preconception hormonal assessment should include:

• •Day 3 FSH, LH, and estradiol: to assess ovarian function and cycle health at baseline
• •Mid-luteal progesterone (day 21 or 7 days before expected period): to confirm ovulation occurred and assess corpus luteum function
• •AMH: for ovarian reserve assessment; can be drawn on any day of the cycle
• •Comprehensive thyroid panel: TSH, free T4, free T3, anti-TPO antibodies, anti-TG antibodies
• •Nutrient levels: vitamin D, ferritin/iron studies, B12 — the nutrients most critical for fertility and early pregnancy
• •Androgens (if PMOS (formerly PCOS) suspected): free and total testosterone, DHEAS, SHBG
• •Semen analysis for the male partner: sperm count, motility, morphology — a standard first step that should happen in parallel, not as a last resort

The PMOS fertility approach

PMOS (formerly PCOS) is the most common cause of ovulatory infertility, but it is also one of the most responsive to root-cause intervention. Because insulin resistance drives the excess LH and androgen production that prevents ovulation in most PMOS cases, blood sugar regulation is the primary fertility intervention. A low-glycaemic diet, consistent exercise (which improves insulin sensitivity independently of weight loss), inositol supplementation (particularly myo-inositol and d-chiro-inositol in a 40:1 ratio), and stress management can restore regular ovulation in many women with PMOS — without pharmaceutical intervention.

Fertility is not simply a matter of timing intercourse correctly. It's the downstream expression of hormonal health — and hormonal health is something you have far more influence over than most women are told. The 3–6 months before conception are among the most impactful of your reproductive life. The work you do in that window — the nutrients you build, the cycles you regulate, the stress you reduce — lays the foundation not just for conception, but for the health of your future pregnancy and your child.