Fertility and hormone health for women: a practical guide with Dr. Natalie Crawford

Executive overview

Fertility is not just about getting pregnant — it is a window into metabolic, hormonal, and cellular health across a woman's lifespan. Poor fertility outcomes are associated with elevated chronic inflammation, insulin resistance, and early mortality, making the same lifestyle factors that support general health directly relevant to reproductive health.

Dr. Natalie Crawford, a reproductive endocrinologist, outlines an evidence-based, proactive approach to hormone health: track ovulation (not just periods), get an AMH test, and optimise the five non-negotiables of sleep, stress, muscle, food, and toxins in the roughly 60-day "trimester zero" before conception.

The core insight: controlling chronic inflammation is the single most powerful lever across fertility, hormone health, and longevity — and it is largely within your control.

Fertility as a health biomarker

• Women with infertility have higher rates of metabolic syndrome, heart disease, and early death — not because infertility causes these, but because it is often the first sign something is wrong.
• Menstrual cycles, as long as they exist, are a live readout of hormonal health — including into perimenopause.
• Ovarian failure before age 40 is associated with higher ovarian inflammation and autoimmune disease — both modifiable.
• The current medical standard (test only after 12 months of failure) forces people to fail before receiving a diagnosis — a model that needs to change.

AMH: the test everyone should have

• AMH (anti-Müllerian hormone) measures ovarian reserve — how many eggs remain — not egg quality.
• Cost: approximately $79 out of pocket; available at LabCorp or direct-to-consumer platforms like Function Health.
• The American College of OB-GYN recommends against routine AMH testing — Dr. Crawford strongly disagrees.
• A low AMH often indicates treatable underlying causes: autoimmune disease, insulin resistance, endometriosis, smoking.
• AMH informs decisions around timing pregnancy, egg freezing, and IVF — regardless of whether infertility is present.
• AMH is suppressed by hormonal birth control, pregnancy, and postpartum; it is not a perfect test but is far better than no test.

Tracking ovulation — not just cycles

• A regular period does not confirm healthy ovulation; tracking ovulation gives a more sensitive signal.
• Ovulation disorders progress predictably: first a short luteal phase (<11 days), then a long follicular phase, then irregular cycles, then amenorrhoea.
• A shortened luteal phase can be missed by cycle tracking alone and warrants investigation (prolactin, thyroid, AMH, PCOS).
• Targeted intercourse around ovulation (the five-day fertile window) significantly improves monthly pregnancy rates.
• Stop hormonal birth control 3–6 months before trying to conceive to learn ovulation patterns and catch any underlying issues early.

Egg quality, ovarian reserve, and age

• Women are born with all the eggs they will ever have; egg count peaks at six to seven million in utero and declines continuously from birth.
• Egg quality = genetic normalcy + mitochondrial competency (egg competency). It cannot be directly tested — it is approximated by age.
• Fecundability (monthly pregnancy probability) with a same partner: ~20% at age 30, ~11–12% at 35–36, ~5% at 38, ~3% at 40+. None of these are zero.
• Prior live birth with the same partner maintains ~18–20% monthly probability up to age 37 before dropping.
• Egg retrieval for IVF or freezing does not deplete ovarian reserve — it uses eggs already exiting the vault that would otherwise die that month.
• Egg freezing is an investment, not an insurance policy; done at a younger age, it yields three times as many viable eggs as at 37.

Birth control and fertility

• Combined oral contraceptive pill: half-life ~28 hours; ovulation resumes the next cycle after stopping. Does not cause infertility.
• Masking effect: many women were put on the pill for PCOS or irregular cycles without diagnosis; stopping the pill can reveal pre-existing problems.
• Progesterone (hormonal) IUD: thins the endometrial lining; remove at least 6 months before trying to conceive to allow lining to rebuild.
• Depo-Provera (high-dose progesterone injection): a single dose can suppress ovulation for up to 18 months. Avoid if planning pregnancy within 2 years.

Hormone replacement therapy

• Estrogen, progesterone, and testosterone all decline with age; most perimenopausal symptoms are driven by falling estrogen.
• The 12-months-without-a-period definition of menopause is a late and arbitrary threshold — hormone therapy can and should start earlier.
• HRT is cardioprotective, reduces Alzheimer's risk, and protects bone density.
• Premature ovarian insufficiency (before 40) has long been treated with hormone replacement; extending this logic to perimenopause is overdue.
• Women deserve the option to augment hormones to the high end of the normal range, not wait until they are out of range.

The five non-negotiables for hormonal and fertility health

• Sleep: 7–9 hours; FSH and LH are released in early morning hours. Poor sleep doubles infertility rates and lowers egg yield at retrieval. Circadian consistency matters as much as duration.
• Stress: chronic stress increases insulin resistance and disrupts the hypothalamic axis (central command for hormones).
• Muscle: building skeletal muscle is the single most effective mechanism for reversing insulin resistance, which is a key driver of hormonal dysfunction.
• Food: anti-inflammatory diet — high fibre, fruits, vegetables, whole grains, healthy fats (olive oil, nuts, fish, flax), quality protein. Reduce ultra-processed foods, added sugars, and red meat excess. Plant protein servings are associated with better ovulation. Cholesterol (from unsaturated fats) is the backbone for progesterone — do not cut it too low.
• Toxins: reduce endocrine-disrupting chemicals — favour fragrance-free (not "unscented") products, avoid BPA from thermal paper receipts, limit plastics; microplastics accumulate in ovarian tissue.

Supplements with evidence

• CoQ10: robust human data for improved egg and sperm quality. Use in "trimester zero" (60–90 days pre-conception); stop in pregnancy.
• Omega-3 fatty acids: clear association with improved reproductive outcomes.
• Vitamin D: strong association with fertility outcomes; widely deficient.
• Prenatal vitamin with folate: start before trying to conceive, not after.
• Melatonin (1–3 mg, 30 min before sleep): supports egg quality via antioxidant effect on the ovary; especially relevant with endometriosis or unexplained infertility. Many OTC products contain 10x the useful dose.
• Inositol: reduces insulin resistance in PCOS; strong evidence.
• N-acetylcysteine (NAC): supports endometriosis and chronic inflammatory conditions.
• For sperm: L-Carnitine, zinc, and selenium have supporting evidence.
• Biotin caution: >300 mcg/day interferes with lab assays for all steroid hormones (estradiol, progesterone, HCG, TSH, testosterone) — producing false results.

Things to avoid

• Cannabis: decreases egg yield by 25%, fertilisation rates by 28%, and live birth rates. Hugely detrimental to sperm count, quality, and DNA integrity. THC crosses the placenta. No safe level in the periconception period.
• Nicotine/smoking: cigarette smoking is one of the few factors that depletes the ovarian vault directly; associated with earlier menopause. Oral nicotine also impairs ovulation via hypothalamic effects and tanks sperm counts.
• NSAIDs (ibuprofen, naproxen, aspirin) around ovulation: can prevent follicle rupture and egg release. Safe to take only during menstruation if trying to conceive.
• High-dose curcumin supplements: not recommended; cooking with turmeric is fine.
• Cold plunges when trying to conceive: may blunt the acute inflammatory response required for follicle rupture and implantation.

Endocrine disruptors

• Phthalates (from fragranced products), BPA, and PFAS impair hormone signalling and lengthen time to pregnancy.
• The EARTH Study shows higher endocrine-disruptor exposure correlates with fewer eggs retrieved, fewer embryos, and poorer sperm counts even in IVF cycles.
• Frequency of exposure matters most — daily products in your home are the priority to clean up.
• "Unscented" ≠ fragrance-free; choose fragrance-free labels.
• Avoid lavender, tea tree, and evening primrose in high-dose supplemental form (topical cooking-level use is low-risk).

Advanced and emerging interventions

• GLP-1 agonists (low dose): showing promise for reducing chronic inflammation in endometriosis and unexplained infertility, independent of weight loss. Not yet a standard recommendation; used adjunctively in select cases.
• Human growth hormone (low dose during IVF stimulation): used off-label when egg maturity or embryo development is poor; increasingly adopted.
• Platelet-rich plasma (PRP): most evidence for intrauterine PRP in recurrent implantation failure; ovarian PRP is more invasive and still experimental.
• Advanced paternal age (>50): increases risk of new autosomal dominant mutations, autism, and schizophrenia in offspring. Banking sperm earlier is worthwhile.