One of the most common questions I hear is some version of: "Am I too early, or too late, to see a fertility dietitian?" The honest answer is that there isn’t an ideal window, starting at any time can make a meaningful difference.
The 90-day window
Eggs take roughly 90 - 100 days to mature before ovulation. This is why three to six months before you plan to start trying is generally considered the ideal time to begin nutritional preparation (although twelve months before is also great). It gives changes to diet and lifestyle, like eating more fruits & vegetables¹, folate-rich foods² and taking a prenatal supplement³ time to influence the eggs that will actually be ovulated.
The same logic applies to sperm, which take around 70-90 days to fully develop. This is a key reason behind starting early where possible, whether you're trying to conceive naturally or preparing for IVF. As a specialist online fertility dietitian in the UK, I work with couples during this window to build highly tailored preconception protocols from the comfort of home.
Egg quality isn't the only clock running
The 90-day window is what people often hear most about but it only tells part of the story. For some clients, the timeline that matters most isn't about egg maturation at all. It's about how long it takes to regulate an underlying hormonal picture.
PMOS (recently renamed from PCOS), for example, often involves insulin resistance and hormone signalling that has built up over years. Diet and lifestyle changes can meaningfully improve symptoms and cycle regularity but this tends to be a more gradual process, usually 6+ months of consistent change before cycles start to regulate. That's a good reason to start earlier rather than later if you know PMOS is part of your picture.
The same applies to irregular or absent periods more broadly (including if your cycles have stopped due to very low body fat, high stress or overtraining). Restoring regular ovulation here is about giving the body consistent signals of safety and adequate energy over time, so again, earlier support tends to be important.
If you're preparing for IVF, the 3-month window lines up well with when many clinics like to start but treatment can also move faster than that. If you already have a start date, it's worth getting support as soon as you can rather than waiting.
And if you have experienced recurrent losses or have higher nutrient needs (for example, folate), where possible, it’s worth reviewing with a dietitian a couple of months before trying again.
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Ella Pomfret is an HCPC registered specialist supporting individuals and couples virtually across the country.
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The “ideal” time and the “only” time are different things.
If you're already partway through trying, already mid-way through an IVF cycle or have been trying for a while without success, nutrition can still play a role. It won't undo time that's passed but it can still help to reduce oxidative stress on developing eggs, support hormonal regulation and improve the nutritional foundations for implantation and early pregnancy. I regularly work with clients who are:
Just starting to think about conception, with lots of lead time
Partway through trying and looking for a clearer, evidence-based plan
Preparing for or in the middle of an IVF cycle
Managing a diagnosis like PMOS, unexplained infertility or recurrent miscarriage
Over 35, where oxidative stress plays a larger role in egg quality and nutrition support is particularly valuable
There's no point at which it's "too late" to benefit from evidence-based nutrition support, the goal simply shifts slightly depending on where you are.
What if you're not sure yet?
You don't need a referral or a medical diagnosis to get started. If you're unsure whether targeted nutrition is a missing piece in your fertility journey, let's explore your timeline together.
👉 Click here to book a free 15-minute discovery call with me. We will look at where you are on your journey and outline exactly how evidence-based nutritional support can help.
Want to start tracking your nutrition today?
If you aren't ready for a 1:1 call just yet, you can download the Free 90-Day Egg Quality Plan to begin making clinical, evidence-based dietary shifts right now, wherever you are in your journey.
References:
Panth N, Gavarkovs A, Tamez M, Mattei J. The Influence of Diet on Fertility and the Implications for Public Health Nutrition in the United States. Front Public Heal [Internet]. 2018 Jul 31 [cited 2026 Oct 7];6:211.
Ebisch IMW, Thomas CMG, Peters WHM, Braat DDM, Steegers-Theunissen RPM. The importance of folate, zinc and antioxidants in the pathogenesis and prevention of subfertility. Hum Reprod Update [Internet]. 2007 Mar 1 [cited 2026 Oct 2];13(2):163–74.
Schaefer E, Nock D. The Impact of Preconceptional Multiple-Micronutrient Supplementation on Female Fertility. Clin Med Insights Women’s Heal [Internet]. 2019 Jan [cited 2026 2026 Oct 7];12:1179562X1984386
