Doctor Guide: Fertility
Doctor Guide: Fertility
Written by BePurer's medical advisory team. For educational purposes only — always consult your GP or fertility specialist for personalised advice.
The evidence on preconception health
The quality of both eggs and sperm is significantly influenced by lifestyle and nutritional factors in the 3–6 months before conception. This is because egg maturation takes approximately 90 days, and sperm production takes approximately 74 days. Interventions made today affect the gametes that will be involved in conception 3 months from now.
Preconception health for women
Nutrition
A Mediterranean-style diet — rich in vegetables, legumes, whole grains, oily fish, olive oil, and nuts — has the strongest evidence base for fertility. It reduces inflammation, supports hormonal balance, and provides the micronutrients essential for egg quality and implantation.
Key dietary principles:
- Prioritise whole foods over ultra-processed foods
- Include oily fish 2x per week (sardines, mackerel, salmon) for omega-3
- Eat iron-rich foods with vitamin C to enhance absorption
- Include eggs daily for choline
- Limit alcohol (ideally avoid entirely when trying to conceive)
- Limit caffeine to under 200mg daily (approximately 2 cups of coffee)
Supplement protocol
- Methylfolate: 400–800mcg daily (start 3 months before trying to conceive)
- Vitamin D3: 1,000–2,000 IU daily (test and optimise to 75–150 nmol/L)
- CoQ10 (ubiquinol): 200–600mg daily (particularly important over 35)
- Omega-3 DHA+EPA: 500–1,000mg daily
- Iron: Test ferritin; supplement if below 50 mcg/L
- Myo-inositol: 2–4g daily if PCOS or insulin resistance is present
- Vitamin E: 400 IU daily as an antioxidant
Lifestyle
- Exercise: Moderate exercise supports fertility; excessive high-intensity exercise can suppress ovulation
- Sleep: 7–9 hours per night; poor sleep disrupts reproductive hormones
- Stress: Chronic stress elevates cortisol, which can suppress GnRH and disrupt the menstrual cycle
- Weight: Both underweight (BMI under 18.5) and overweight (BMI over 30) are associated with reduced fertility
- Smoking: Accelerates ovarian ageing and reduces egg quality significantly
Preconception health for men
Male factor infertility contributes to approximately 50% of fertility challenges. Sperm quality is highly responsive to lifestyle changes — and improvements can be seen within 3 months.
Supplement protocol for men
- CoQ10: 200–400mg daily
- Zinc: 25–30mg daily
- Selenium: 55–200mcg daily
- Vitamin C: 500–1,000mg daily
- Omega-3: 500–1,000mg EPA+DHA daily
- Folate: 400mcg daily
- Vitamin D: 1,000–2,000 IU daily
Lifestyle for men
- Avoid tight underwear and hot baths (heat impairs sperm production)
- Limit alcohol and avoid recreational drugs
- Quit smoking
- Maintain a healthy weight
- Avoid anabolic steroids (severely impair sperm production)
When to seek specialist help
- Under 35: after 12 months of regular unprotected sex without conception
- Over 35: after 6 months
- Any age: if there is a known condition affecting fertility (PCOS, endometriosis, thyroid disorder, previous pelvic infection)
- Any age: if periods are absent or very irregular
- Any age: if there is a history of recurrent miscarriage (2 or more)