Fertility & Preconception Nutrition

Preparing for pregnancy is more than taking a prenatal - it’s about creating a strong foundation for your body, hormones, and future.

Understanding the Preconception Window: Why It Matters

The time before conception is more than just "waiting to get pregnant." It's an important window that sets the stage for fertility, early development, and long-term health of both you and your future baby.

The three months before conception are particularly significant. This is the time it takes for:

  • An egg to mature fully (folliculogenesis)

  • Sperm to develop and undergo DNA packaging

  • Nutrient stores (like folate, iron, and vitamin D) to be replenished

  • Hormones (like insulin, thyroid hormones, and progesterone) to stabilize

Key goals during the preconception window include:

  • Optimising folate and B vitamin levels to reduce neural tube defects

  • Reducing oxidative stress to support egg and sperm quality

  • Managing blood sugar levels and insulin resistance

  • Addressing any underlying deficiencies (iron, iodine, vitamin D)

  • Supporting a healthy weight for your height (BMI) and reducing excess visceral fat (unlike the fat just under your skin, our ‘cuddly bits’, this type wraps around your liver, kidneys, and other organs and can affect your health)

Your Menstrual Cycle: Nutrition by Phase

Understanding your cycle isn’t just helpful for timing ovulation - it can guide how you eat, move, and supplement throughout the month. Each phase brings unique hormonal shifts, and your nutritional needs shift in response.

Fertility Nutrition: What to Focus On

What you eat plays a key role in reproductive health. It influences hormone balance, egg development, and the lining of your womb. Aim to begin making changes at least 3 months before trying to conceive, as egg maturation and sperm development each take around 90 days.

Key nutrients and food sources:

  • Folic Acid

    Folic acid plays a crucial role in supporting the early development of your baby’s brain and spinal cord. Supplementation before conception and during early pregnancy helps reduce the risk of neural tube defects (NTDs), such as spina bifida.

    • General recommendation:
      Most women are advised to take 400 µg (0.4 mg) of folic acid daily from at least 12 weeks before conception until the end of the first trimester.

    • Higher-dose recommendation:
      A 5 mg daily folic acid supplement is usually recommended for women at higher risk of NTDs. This includes those who:

      • Have diabetes

      • Have a BMI ≥ 30 kg/m²

      • Take certain anti-epileptic medications

      • Have a personal or family history of neural tube defects

      • Have coeliac disease, thalassaemia, or other conditions affecting folate absorption

      This higher dose is typically prescribed by a healthcare professional.

    • Methylated form:
      Ideally, choose a methylated form of folate (5-MTHF) for better absorption, especially if you have the MTHFR gene variant, which can reduce your ability to convert folic acid into its active form.

    Tip: Start your folic acid or folate supplement before trying to conceive - ideally at least 12 weeks beforehand - as the neural tube develops very early in pregnancy, often before you know you’re pregnant.

    Food sources of folate:
    Leafy greens (like spinach, kale), legumes (beans, lentils), asparagus, citrus fruits (especially oranges), and fortified grains.

  • Iron 

    Essential for ovulation and red blood cell production.

    Animal sources: red meat, liver, poultry.

    Plant sources: lentils, spinach, chickpeas.

    Tip: Pair with vitamin C (like citrus, strawberries, or red peppers) to enhance absorption.

  • Zinc

    Supports egg quality, hormone regulation, and sperm health.

    Sources: shellfish, pumpkin seeds, legumes.

    7 mg/day is the UK reference intake for adult women (preconception and beyond).

    But routine zinc supplementation is not mandated under UK national maternal health guidelines (unlike folic acid or vitamin D).

  • Omega-3s (250–500 mg EPA/DHA/day)

    Anti-inflammatory and supportive of implantation, hormone synthesis, and egg development.

    Two different types to include: DHA (docosahexaenoic acid) is especially important for brain and cell health, while EPA (eicosapentaenoic acid) supports inflammation reduction.

    Sources: oily fish like salmon, mackerel, sardines; algae-based supplements for vegetarians.

  • Iodine

    Essential for thyroid hormone production, which supports your metabolism and your baby’s brain development during pregnancy. Deficiency can affect fertility, ovulation, and foetal neurodevelopment.

    • UK guidance:
      The UK Reference Nutrient Intake (RNI) for women is 140 µg/day, including during pregnancy and lactation.
      However, international recommendations (e.g. WHO) often cite 150 µg/day as the target intake for adults, including women planning pregnancy.

    • Supplementation:
      Unlike folic acid and vitamin D, iodine supplementation is not routinely recommended for all pregnant women in the UK, but women are encouraged to achieve adequate intake through diet. In some prenatal supplements, iodine (around 150 µg) is included - this can help meet requirements, especially for those avoiding dairy or fish.

    • Food sources:
      Dairy products, white fish, and eggs. (Seaweed with caution - iodine content in seaweed is highly variable, and excessive intake can be harmful).

Note: Vegan or dairy-free diets are associated with a higher risk of iodine deficiency. In these cases, a supplement containing around 150 µg iodine (from potassium iodide or potassium iodate) is often advisable - ideally discussed with a healthcare professional.

  • Selenium

    Adequate intake is linked to better egg quality.

    UK guidance: 60 µg/day for adult women

    There are no additional selenium supplementation recommendations in pregnancy in the UK, but ensuring dietary adequacy is important.

    Food sources:
    Brazil nuts (1–2 per day can meet daily needs), seafood, eggs, poultry, and whole grains.

Excess selenium can be toxic - avoid high-dose supplements unless advised by a clinician. Most prenatal vitamins contain safe, modest amounts (e.g. 30–70 µg).

  • Choline (450 mg/day)

    An essential nutrient that plays a key role in early brain and neural development, as well as egg maturation and cell membrane formation.

    UK guidance:
    There is no official Reference Nutrient Intake (RNI) for choline in the UK yet. However, international bodies - including the US Institute of Medicine and EFSA - recommend around 450 mg per day during pregnancy and 550 mg per day during lactation.

    Supplementation:
    Unlike folic acid, choline supplementation is not routinely included in UK prenatal vitamins, even though many women fall short of the recommended intake through diet alone. Including choline-rich foods regularly or choosing a prenatal with added choline can help bridge this gap.

    Food sources:

    • Eggs (especially the yolks)

    • Liver

    • Soybeans and other legumes

    • Lean meats and fish

Note: One large egg contains roughly 125–150 mg of choline, making eggs one of the richest and most practical sources - especially during preconception and pregnancy.

  • Aim for a Mediterranean-style pattern: Think plant-forward, rich in healthy fats, bursting with colourful produce, and built around minimally processed foods.

    A Mediterranean-style dietary pattern has consistently been linked to improved fertility outcomes, better pregnancy health, and long-term benefits for both parent and baby. It emphasises quality, variety, and balance, rather than restriction.

    Core principles include:

    • 🥦 Plenty of plants – Make vegetables, fruits, legumes, nuts, seeds, and whole grains the foundation of your meals. Aim for a rainbow of colours to maximise antioxidant and phytonutrient intake.

    • 🫒 Healthy fats – Prioritise extra-virgin olive oil, nuts, seeds, and oily fish (e.g. salmon, sardines, mackerel) for omega-3 fatty acids, which support hormone production, egg quality, and baby’s brain development.

    • 🐟 Lean proteins – Include a mix of plant-based proteins (e.g. beans, lentils, tofu) and lean animal sources like poultry, fish, eggs, and occasional red meat.

    • 🍞 Whole, minimally processed foods – Choose whole grains over refined, cook from scratch when possible, and keep ultra-processed foods and added sugars to a minimum.

    • 🍷 Alcohol – Limit or avoid when trying to conceive, and avoid completely during pregnancy.

Supplement Guidance

Weight & Fertility

Body weight - whether lower or higher than average - can influence ovulation and hormone balance. While a BMI in the ‘healthy’ range (18.5–25) is often recommended in fertility guidance, it’s important to remember that BMI is only one piece of the puzzle. You don’t need to reach a specific number to conceive - but understanding how weight might impact your cycle can be helpful:

  • In underweight individuals (BMI less than 18.5 kg/m2), low leptin and fat stores can delay or suppress ovulation.

  • In higher BMI ranges (more than 30 kg/m2), insulin resistance and excess estrogen can affect regular cycles.

What matters more than the number:

  • Supporting blood sugar stability (through protein, fibre, and healthy fats)

  • Encouraging gentle movement (e.g. walking, strength training)

  • Managing stress and sleep, which also impact hormones

If weight is a focus, the goal is gentle, sustainable change, not restriction.

A Note on GLP-1 Medications (e.g. Ozempic, Wegovy, Mounjaro)

GLP-1 receptor agonists and similar medications are increasingly used to support weight management and metabolic health. While these medications can be helpful tools for some, they are not recommended during pregnancy or while trying to conceive.

Here’s why:

  • Most GLP-1s have not been tested for safety in pregnancy, and current evidence advises stopping them at least 1–2 months before conception.

  • They can impact nutrient absorption, appetite, and weight loss pace - all of which are important to stabilise before pregnancy.

  • Some may contribute to gastrointestinal symptoms (like nausea or vomiting), which could compound early pregnancy discomfort or affect intake.

If you’re using a GLP-1 medication and considering pregnancy, it’s important to:

  • Consult your prescriber or specialist to make a tapering or transition plan.

  • Work with a registered dietitian to support a smooth off-ramp and establish nutrition foundations for conception.

Lifestyle & Fertility

You don’t need to live perfectly to support your fertility - but small, consistent lifestyle shifts can help create a more supportive internal environment for conception. These changes don’t require an overhaul, but they can play a valuable role in supporting hormonal harmony, a healthy menstrual cycle, and fertility.

Supportive habits to prioritise:

  • Sleep: Aim for 7–8 hours of quality sleep each night. Disrupted or inadequate sleep can raise cortisol (your stress hormone), which may interfere with ovulation and hormone regulation.

  • Exercise: Choose movement that’s sustainable and enjoyable. Regular, moderate activity - like walking, resistance training, or yoga - supports insulin sensitivity and reduces inflammation without overstressing the body.

  • Stress Management: Chronic stress can suppress ovulation and lengthen time to conception. Practices such as mindfulness meditation, journaling, breathwork, therapy, or acupuncture can help calm your nervous system and support hormonal balance.

  • Limit Alcohol and Avoid Smoking: Alcohol and tobacco use have been shown to negatively impact egg and sperm quality, potentially increasing the time it takes to conceive. Reducing or eliminating these exposures is a powerful way to support reproductive health.

  • Vaping is not considered a safe alternative to smoking. While marketed as less harmful than smoking, e-cigarettes still expose the body to nicotine and other chemicals, which may negatively impact fertility and are not recommended in pregnancy. Reducing or eliminating these exposures is a powerful way to support reproductive and overall health.

IVF & Assisted Conception

Fertility treatments such as IVF add both physical and emotional layers to the journey of conception. While nutrition alone cannot change the outcome, it can support the foundations that matter most - egg quality, endometrial health, hormone regulation, and overall wellbeing during a physically demanding process.

Evidence suggests that nutritional status before and during IVF is linked to reproductive outcomes, including improved fertilisation rates, embryo quality, and implantation success.

The following information is not meant to replace recommendations already provided to you by your doctor. Always follow the specific guidance provided by your fertility doctor or healthcare team - nutritional support can complement, but not replace, medical treatment.

Support Starts with Both of You

Sperm health is half the story. Like egg quality, it’s influenced by nutrition, lifestyle, and time. Simple, consistent steps - like eating well, reducing exposures, and taking a quality multivitamin - can make a meaningful difference when trying to conceive.

Sperm take around 72–90 days to fully mature. This means the choices made in the 3 months before conception can significantly impact sperm count, motility (movement), morphology (shape), and DNA integrity