Questions men actually ask.

Roughly two to three months. New sperm are made continuously in a process called spermatogenesis, and the classic estimate of its duration in men is about 74 days from stem cell to sperm, followed by one to two weeks of maturing in the epididymis. A 2006 study using a stable-isotope tracer put the core process nearer 64 days, which is why Motily talks about the timing as rough rather than exact.

Either way, a change you make today, such as cutting back on drinking or fixing your sleep, takes about two to three months to show up in the sperm you actually produce. That's why Motily's journey runs for 74 days, and why a semen analysis taken a week into a new routine mostly reflects the old one.

Sources: Heller CG, Clermont Y. Spermatogenesis in man: an estimate of its duration. Science, 1963. Misell LM, et al. A stable isotope-mass spectrometric method for measuring human spermatogenesis kinetics in vivo. Journal of Urology, 2006.

Research suggests it does. A study of 953 young Danish men found that those reporting the most sleep disturbance had sperm concentrations around 29% lower than men with little disturbance, and a longitudinal Chinese study found an inverse U shape: both short (6.5 hours or less) and long (over 9 hours) sleep were linked to lower semen volume and sperm number than 7 to 7.5 hours. Around 7 to 8 hours a night, at a consistent bedtime and wake time, is generally considered the sweet spot.

These are observational studies, so they show a link rather than proof of cause. Motily scores sleep on hours and asks about quality, and can prefill the hours from Apple Health.

Sources: Jensen TK, et al. Association of sleep disturbances with reduced semen quality: a cross-sectional study among 953 healthy young Danish men. American Journal of Epidemiology, 2013. Chen Q, et al. Inverse U-shaped association between sleep duration and semen quality: longitudinal observational study (MARHCS) in Chongqing, China. Sleep, 2016.

Heavy or daily drinking is linked to lower semen volume and poorer sperm quality. Light to moderate drinking shows less clear effects: a 2017 systematic review and meta-analysis found the consistent association was with daily or heavy intake rather than occasional drinks.

Motily scores each day's alcohol on a sliding scale, so an alcohol-free day scores full points, one drink costs a little, and four or more costs the most. A few extra alcohol-free days a week is the simplest change. Caffeine is scored separately, and moderate intake (up to two or three cups) isn't penalized, because a 2017 review didn't find a consistent link between coffee and semen quality.

Sources: Ricci E, et al. Semen quality and alcohol intake: a systematic review and meta-analysis. Reproductive BioMedicine Online, 2017. Ricci E, et al. Coffee and caffeine intake and male infertility: a systematic review. Nutrition Journal, 2017.

Smoking, yes, and it's one of the most consistently confirmed lifestyle factors. A 2016 meta-analysis of more than 5,000 men found smokers had lower sperm count, lower motility and poorer morphology, with the effect strongest in moderate and heavy smokers. There's no safe amount, so Motily scores even light smoking steeply. Quitting entirely is one of the single biggest wins available to you.

Vaping has far less research behind it. One 2020 study of 2,008 young Danish men found daily e-cigarette users had lower total sperm counts than non-users, but it's a single observational study and the picture is still forming. Motily treats vaping as a substance to log, and is honest that the evidence is thinner than for cigarettes.

Sources: Sharma R, et al. Cigarette smoking and semen quality: a new meta-analysis examining the effect of the 2010 World Health Organization laboratory methods for the examination of human semen. European Urology, 2016. Holmboe SA, et al. The association of reproductive hormones with sperm quality and e-cigarette and marijuana use in young men. Human Reproduction, 2020.

Extra heat around the testicles can temporarily lower sperm production, and the effect is generally reversible once the exposure stops. In a small 2013 study, two 15-minute sauna sessions a week for three months reduced sperm count and motility in ten healthy men, and both were back to baseline by the six-month follow-up.

On underwear, a 2018 study of 656 men attending a fertility center found those who mostly wore boxers had higher sperm concentration and total count than those who mostly wore tighter styles. Motily asks each day which heat exposures applied, and the best answer is none of them. Simple swaps, like a lap desk and looser, breathable underwear, are permanent fixes.

Sources: Garolla A, et al. Seminal and molecular evidence that sauna exposure affects human spermatogenesis. Human Reproduction, 2013. Mínguez-Alarcón L, et al. Type of underwear worn and markers of testicular function among men attending a fertility center. Human Reproduction, 2018.

Research suggests a sweet-spot effect. A 2019 systematic review and meta-analysis found physically active men had better semen quality on several measures than inactive men, while other work links very high-volume, high-intensity training (for example, competitive cycling) to poorer results. Moderate and regular beats none or extreme.

Motily's daily target is 25 to 45 minutes of moderate activity, and it scores a very long single session slightly below that band rather than penalizing it, because the overtraining concern is really about sustained weekly volume. If you're currently sedentary, a daily walk is a legitimate starting point.

Source: Ibañez-Perez J, et al. An update on the implication of physical activity on semen quality: a systematic review and meta-analysis. Archives of Gynecology and Obstetrics, 2019.

It appears to. A 2013 collaborative meta-analysis of 21 studies found that men in the overweight and especially the obese BMI range were more likely to have a low sperm count or no sperm at all than men of normal weight, with a smaller effect at the underweight end.

Motily uses your height and weight from the onboarding quiz to include BMI in your Overall score, and its tip is gradual, sustainable change toward a healthy range rather than quick fixes.

Source: Sermondade N, et al. BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis. Human Reproduction Update, 2013.

Probably, though the evidence is mixed. A 2014 study found men reporting two or more stressful life events in the past year had lower motility and morphology, but a 2016 study of 1,215 Danish men found self-rated stress was linked to lower semen quality only at the highest stress levels, with no clear effect at moderate levels. The proposed mechanism runs through stress hormones like cortisol affecting testosterone.

This is about general wellbeing trending the right way, not any single stressful day, and eliminating stress entirely isn't realistic for most people. Motily asks how many stressful episodes you had and how you felt. The things that tend to help most are small and repeatable: a short walk, a few minutes of breathing, stepping outside. Regular exercise and consistent sleep both indirectly support mood.

Sources: Janevic T, et al. Effects of work and life stress on semen quality. Fertility and Sterility, 2014. Nordkap L, et al. Psychological stress and testicular function: a cross-sectional study of 1,215 Danish men. Fertility and Sterility, 2016.

More whole, unprocessed food and less ultra-processed food. A 2017 systematic review of observational studies found diets rich in vegetables, fruit, fish, poultry, whole grains and low-fat dairy were linked with better semen quality, while diets high in processed meat, full-fat dairy, sweets and sugary drinks were linked with worse. The nutrient groups worth knowing about: antioxidant-rich foods (berries, walnuts, leafy greens, tomatoes), omega-3s (oily fish, flaxseed), zinc and selenium (oysters, pumpkin seeds, Brazil nuts) and folate (leafy greens, lentils, chickpeas).

Supplements are less clear-cut. The 2019 Cochrane review of antioxidant supplements found they may increase live birth and pregnancy rates in subfertile couples, but rated the evidence low quality because of small, inconsistent trials. Food first, and check with a clinician before starting supplements, especially alongside medication. Motily's nutrition check-in asks roughly what share of your food was whole, whether you took a supplement, and your caffeine.

Sources: Salas-Huetos A, Bulló M, Salas-Salvadó J. Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies. Human Reproduction Update, 2017. Smits RM, et al. Antioxidants for male subfertility. Cochrane Database of Systematic Reviews, 2019.

More often than folklore suggests. The American Society for Reproductive Medicine's committee opinion supports intercourse every one to two days during the fertile window (roughly the five days before ovulation plus ovulation day) and every two to three days across the rest of the cycle, over saving up for one big day.

Frequent ejaculation doesn't harm sperm quality: a 2016 study that had 20 men ejaculate daily for two weeks found volume, concentration and total motile count fell, mostly in the first three days, while motility and morphology were unchanged, and shorter abstinence is linked to healthier sperm DNA in several studies. Most standard lubricants, and saliva, can slow sperm down, so if you need one, choose a fertility-friendly product.

Sources: Practice Committee of the American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertility and Sterility, 2022. Welliver C, et al. Analysis of semen parameters during 2 weeks of daily ejaculation: a first in humans study. Translational Andrology and Urology, 2016.

The NHS advises seeing a GP if you haven't conceived after a year of regular unprotected sex, and sooner if your partner is 36 or over or either of you has a known fertility issue. ASRM uses 6 months when the woman is 35 or older. Ask sooner if you have a known factor on your side: a varicocele, an undescended testicle, mumps after puberty, groin or testicular surgery, past chemotherapy or radiotherapy, or testosterone or anabolic steroid use. That's a proactive step, not a sign anything's wrong.

Motily can't do any of this for you. It doesn't diagnose, doesn't treat, and doesn't guarantee any outcome. It's a lifestyle tool, not a medical device, and it hasn't been assessed by any medical regulator. It can't tell you whether you're fertile, and it doesn't replace a semen analysis, a urologist or a fertility specialist.

Sources: NHS. Infertility. Practice Committee of the American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertility and Sterility, 2022.

Emerging research suggests they might, in ways beyond sperm count alone. A father's diet, weight, smoking, alcohol use, stress and toxin exposure before conception can alter chemical markers on sperm, such as DNA methylation, that influence how genes switch on and off without changing the DNA sequence itself.

Most of the strongest evidence so far comes from animal studies, with human research still catching up, so treat it as a promising, still-developing picture rather than settled fact, and one more reason the months before conception are worth taking seriously.

Source: Soubry A, et al. A paternal environmental legacy: evidence for epigenetic inheritance through the male germ line. BioEssays, 2014.

A standard semen analysis reports semen volume, sperm concentration, total sperm count, total motility and progressive motility, and often morphology, pH and vitality. The WHO Laboratory Manual for the Examination and Processing of Human Semen, 6th edition (2021), gives lower reference limits taken from the 5th centile of men whose partners conceived within a year:

A result below a limit means below reference, not infertile: plenty of men below these limits have children, and plenty above them don't. Results also vary a lot between samples, which is why clinics often repeat the test. Motily shows each value you enter against these limits and tracks the trend between reports, and leaves interpretation to your clinician. DNA fragmentation and antisperm antibodies aren't WHO reference limits; where the app shows tiers for them it uses commonly cited laboratory cut-offs.

Source: World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th edition. Geneva, 2021.

There are two scores. Your Today score is out of 100 and climbs as you log the day's eight categories, weighted roughly by how strong and consistent the research is for each: nutrition 18, substances 18, sleep 16, exercise 12, heat 10, mood and stress 10, intercourse 10, hydration 6.

Your Overall score starts from your onboarding quiz (which also includes age, BMI, underwear and sitting time) and blends each overlapping category 50/50 with the average of your last seven days, so recent behavior counts as much as your baseline without a single day swinging it.

Both are estimates built from what you tell the app. Neither is a measure of your fertility, and neither can tell you whether you can or cannot conceive.

Almost everything Motily stores about you is health data, and some of it concerns your sex life, so it's treated as special category data under UK GDPR and processed only with your explicit consent. It's stored with Supabase in its London region, every table is protected by row-level security, and no advertising SDKs, ad identifiers, location or cross-app tracking are used. Motily doesn't sell your data. A crash reporter (Sentry, EU region) and a usage counter (PostHog, EU cloud) help keep the app working, and neither ever receives your answers, scores or report values; the usage counter can be switched off in Profile. You can delete your account and everything tied to it yourself, immediately, from Profile. Read the full privacy policy.

Your partner sees only what you choose to share, and never your answers. The partner page needs no app and no account: she opens a link, enters the 6-character code from your Profile, and sees which day of the 74-day journey you're on, your streak and Perfect Days, and whether today's check-in is done. She can send a nudge that shows up in your app. She can't see your score, your check-in answers, your quiz answers, your semen analysis or your Community identity, and the read path is a whitelist enforced on the server. Either of you can disconnect at any time. Optionally, and with clear consent, she can share her last period date and cycle length so her fertile window shows on your Today tab; that part is Premium.

During the beta, nothing. Everyone gets an automatic welcome week of Premium, and while the beta runs, choosing a plan unlocks Premium at no cost with no payment details collected. Free always includes daily check-ins, your Today and Overall scores, streaks, the 74-day journey, your first semen analysis interpreted, the partner page and Community. The planned Premium prices after the beta are £9.99 a month or £54.99 a year, and Premium adds the score breakdown, trends beyond this week, interpretation of every semen analysis you log, the partner fertile-window sync and, soon, a weekly report. If paid plans arrive, you'll hear about it in the app first, with notice, and payments would go through the App Store.

The beta is iPhone only, installed through Apple's TestFlight, and Apple Health prefill is iOS only too. The partner page is a website, so a partner on Android can use it today. If you want Motily on Android, email [email protected] and say so; it helps decide what comes next.