Thinking about starting a family? Whether you're actively trying or just want to understand your options, the useful move is the same: get a baseline picture of your reproductive health. Most fertility advice waits until you're already trying and something isn't working. That's the wrong end of the timeline. The earlier you understand your cycle, your hormones, and your vaginal health, the more you can actually do about them.

This guide covers what the evidence supports, where it's genuinely uncertain, and which checks are worth doing now rather than later.

Your cycle is a monthly health signal

A typical cycle runs 21 to 35 days. What matters isn't the exact number, it's the consistency. Regular cycles are a reasonable sign that your hormones are doing their job. Cycles that swing widely month to month can point to something worth looking into, most commonly PMOS, formerly PCOS, or a thyroid issue, both of which are manageable once identified.

Worth flagging to a clinician if you notice:

• Irregular or missing periods
• Swelling of the thyroid
• Severe period pain that disrupts your life
• Unusually heavy bleeding, where you need to use more than 1 tampon or 1 pad every 2 hours
• Sudden acne or excess hair growth, such as hair on your chin, nipples or back
• Significant, unexplained weight changes

None of these mean you can't conceive. They mean the underlying cause is worth understanding early, while you have time to act on it.

Finding your fertile window

Here's the part most people get wrong: conception is only possible for two to six days each cycle. The egg lives for roughly 24 hours after ovulation. Sperm can survive up to five days in the reproductive tract. So the days that matter are the ones leading up to ovulation, not after. Timing sex to the day of ovulation is already slightly late.

Four ways to find your window, roughly in order of reliability:

Ovulation predictor kits (OPKs). These detect the LH surge in urine, which happens 24 to 36 hours before ovulation. Start testing two to three days before you expect to ovulate. This is the most practical predictive method for most people. It’s also affordable as a lot of these kits are available over the counter in your local retail pharmacy. 

Cervical mucus. As you approach ovulation, mucus becomes clear, stretchy, and slippery, similar to raw egg white. It's free, and once you know what to look for it's a genuinely useful real-time signal.

Basal body temperature (BBT). Take your temperature every morning before getting up, or use a tracker like Daye partner, Natural Cycles. A sustained rise of 0.3 to 0.5°C confirms ovulation happened. The catch: it tells you after the fact, so it's better for spotting patterns across cycles than for timing a single one.

Tracking apps. Good for logging and spotting your own patterns over time. Treat their predictions as estimates, not gospel, especially if your cycle is irregular. Daye partner, Clue, uses validated algorithms to predict your ovulation.

Combine a couple of these across a few cycles and you'll build a clearer picture of your ovulation window. Then you can focus effort on the days that count.

The fertility factor most guides skip: your vaginal microbiome

This is the part of fertility prep that rarely gets airtime, and it may be one of the most actionable.

A healthy vagina is dominated by Lactobacillus bacteria, which keep the environment acidic and protective. That environment does two jobs at once: it defends against infection, and it's the environment sperm have to survive and travel through. When that balance is disrupted, you can end up with conditions like bacterial vaginosis (BV) or thrush, often with mild or no symptoms.

Why this matters for conception: research links a vaginal microbiome low in Lactobacillus to lower success rates in IVF and embryo transfer. The direction of the evidence is consistent enough that vaginal health deserves a place in the fertility conversation, not a footnote at the end.

The practical takeaway: BV and other imbalances are common, frequently silent, and treatable. Knowing where you stand is cheap insurance before you start trying.

Daye's Diagnostic Tampon screens your vaginal microbiome at home, alongside common infections, so you're not guessing about something that's straightforward to test and treat. It's part of the Fertility Focus Bundle, covered in full below.

The silent threats: STIs and HPV

Some of the most preventable causes of fertility problems cause no symptoms at all until damage is already done.

Chlamydia is the big one. It's one of the most common STIs and often produces zero symptoms. Left undetected, it can ascend and cause pelvic inflammatory disease, which is a leading preventable cause of tubal-factor infertility, where the fallopian tubes are scarred or blocked. This is well established, not speculative. A single asymptomatic infection you never knew about can quietly affect your fertility years later. Screening is simple and the fix is a course of antibiotics.

HPV is worth screening for primarily because of cervical health: persistent high-risk HPV is the cause of nearly all cervical cancer, and knowing your status lets you stay ahead of it. There's also some early research suggesting HPV may affect pregnancy and fertility outcomes. The cervical-health case alone is reason enough to know your status before pregnancy as you need a healthy cervix to carry a pregnancy to term without complications. 

Both chlamydia and HPV are screened at home with Daye's Diagnostic Tampon, available in the UK & Ireland, on the same sample you'd use for microbiome testing. The screen also covers gonorrhoea, trichomoniasis, and the mycoplasma and ureaplasma bacteria that have been linked to fertility and pregnancy complications.

Fertility testing, honestly

Testing can tell you useful things about your ovarian reserve and hormone levels. It can also be badly oversold and/or hard to access.

AMH (anti-Müllerian hormone) is a marker of ovarian reserve, roughly, how many eggs you have left. It's genuinely useful in one context: if you're considering IVF or egg freezing, AMH helps predict how your ovaries will respond to stimulation, and it's a reasonable prompt to think about timelines if it's low for your age.

Here's what AMH does not do, despite how it's often marketed: it does not reliably predict your chances of conceiving naturally. A large, high-quality study of women without a history of infertility found that AMH and FSH levels were not associated with the likelihood of getting pregnant on their own. So a "normal" AMH is not a green light in isolation, and a lower-than-average AMH is not a verdict. It's one important data point about egg quantity.

Where testing earns its place is in catching the things you can act on: hormonal imbalances behind irregular cycles, thyroid issues, and low vitamin D and iron levels. Those change what you do next. 

This is the logic behind Daye's Fertility Focus Bundle. Instead of a single AMH reading, it runs a full hormone panel, FSH, LH, estradiol, testosterone, thyroid markers, prolactin, SHBG, ferritin, and vitamin D, with AMH included, alongside the vaginal microbiome, STI, and HPV screen and a one-to-one fertility nurse consultation to interpret the results together. AMH becomes one input in a full picture rather than a number read in isolation.

Results you don’t have to decode alone

Most at-home tests end with a PDF and a shrug. You get numbers, maybe a flag on something out of range, and no real sense of what to do next. That gap is where a lot of the anxiety lives, and it's the part the bundle is built to close.

Every Fertility Focus Bundle includes a one-to-one video consultation with a fertility clinician who walks you through your hormone and microbiome/STI results and translates them into what actually matters for your situation, whether you're trying now or planning years ahead. It starts before you even test: a short onboarding call helps you take each sample at the right point in your cycle, so the results are usable rather than muddied by bad timing.

These aren't generalists reading off a script. Daye's team includes fertility nurses and specialist midwives with years of experience in reproductive health, hormone health, and the vaginal microbiome, and any follow-up treatments are delivered through CQC-regulated providers. If a result is out of range, they'll tell you what it means, whether it's worth taking to your GP, and what the sensible next step is, so one worrying number doesn't turn into a week of googling worst-case scenarios.

A reminder that it takes two

Fertility content is overwhelmingly aimed at women, which quietly misleads couples. Male factor is involved in roughly half of cases where a couple struggles to conceive. If you're trying as a couple and it isn't happening, a semen analysis for your partner is one of the simplest, highest-value early tests there is. Don't spend a year optimising one half of the equation while ignoring the other.

Lifestyle changes that actually move the needle

Most fertility lifestyle advice is either obvious ("eat well, sleep more") or wishful. Here are the levers with real evidence behind them, including a few that almost never make the listicles.

It's half his job, and sperm respond fast. Sperm regenerate on a roughly three-month cycle, so a change in his diet shows up in a semen sample within about 90 days, faster than almost any intervention on the female side. The standout evidence is a rare thing in nutrition science: a randomised controlled trial. In the FERTINUTS study, healthy men who added 60g of mixed nuts a day for 14 weeks saw sperm count rise by around 16%, with improvements in motility, vitality and shape, against a control group who ate no nuts. Antioxidant supplements are a related oddity: they appear to help male fertility but do little for women. If you're doing all the optimising on your side of the equation, that's a lopsided plan.

What's on your produce may matter as much as the produce. Fruit and veg are non-negotiable, but pesticide residue is an underrated variable. In Harvard's EARTH study, women in fertility treatment who ate more high-residue produce had lower odds of pregnancy and live birth. Modelling a swap of just one high-residue item a day for a low-residue one was associated with 79% higher odds of pregnancy and 88% higher odds of a live birth. Washing produce well and buying organic for the high-residue "dirty dozen" is a cheap hedge. (It's the same logic behind why we test every batch of Daye tampons for pesticides, heavy metals and "forever chemicals.")

Your gums. This one sounds absurd until you see the numbers. In an Australian cohort of about 3,400 women, those with gum disease took roughly two months longer to conceive, an effect the researchers placed on the same order of magnitude as obesity. The proposed mechanism is chronic oral inflammation leaking inflammatory signals into the bloodstream. The evidence is still early and strongest in some subgroups, but a dental check-up is a painless thing to add to preconception prep.

Folate does more than protect the baby's spine. Everyone knows folic acid prevents neural tube defects, and that alone makes it non-negotiable before conception, it has to be built up in your system before you're pregnant, not started after a positive test. Less well known: higher folate intake is consistently linked to better ovulatory function, lower miscarriage risk and greater success in fertility treatment, which suggests it supports conception itself, not just the pregnancy that follows. 

Skip the standard lubricant. In the lab, many common lubricants, including household names, sharply cut sperm motility, some immobilising sperm within minutes. If you'd rather remove the variable, use one labelled "fertility-friendly" and avoid glycerin-heavy formulas.

The ones you've heard, calibrated honestly. A Mediterranean-style pattern (more plant protein, more monounsaturated fat, fewer ultra-processed foods), protected sleep, and moderate exercise all have reasonable support and are worth doing. Two corrections worth making: vitamin D gets pushed hard for fertility, but the evidence says it does little unless you're actually deficient, so correct a deficiency rather than megadosing a normal level. And with exercise, more isn't better, vigorous training helps most women but can suppress ovulation in those who are already very lean.

If you have PMOS, endometriosis, or another specific condition, treat the advice above as a starting point rather than a plan. The right approach differs enough by condition that personalised guidance is worth it.

Your next step

The most powerful thing you can do when preparing for pregnancy is to stop guessing about the parts of your health you can actually measure. Your cycle, your hormones, and your vaginal health are all things you can get a clear read on before you start trying, when there's still time to act on what you find.

Daye's Fertility Focus Bundle brings the whole picture together in one kit: a full hormone panel plus AMH for ovarian reserve, a vaginal microbiome, STI, and HPV screen, and a 1:1 video consultation with a fertility nurse to walk you through your results and next steps. You collect both samples at home, a pain-free arm device for the blood test and the Diagnostic Tampon for the vaginal sample, and everything is analysed in UKAS-accredited labs. It's £299 for testing that would typically cost around £1,000 done piece by piece.

Whether you're trying now or planning ahead, that's a clear baseline to start from, knowledge instead of hope.