Your Gemel signal isn't a wellness guess. It scores lifestyle factors that peer-reviewed research links to reproductive health — and every factor below points to a real study you can read.
How the score works
We weight each factor by how strong the evidence for it actually is, so well-established levers count more than weak ones:
A Consistent meta-analyses / trialsB Mixed or observationalC Weaker / preliminary (a gentle nudge)
Your signal reflects only the factors you can change. Age is shown as context, never counted against you. The plan targets your biggest evidence-backed wins — and because sperm and egg cells take about 90 days to mature, that's the window over which changes show up.
Factors we score — his side
A Smoking / vapingLowers concentration, motility and morphology, dose-dependently. Sharma 2016 ↗
A Anabolic steroids / TStrongly suppress sperm production — a doctor flag, not a plan item.
B Weight / BMIBoth high and low BMI reduce success and can disrupt cycles. Sermondade 2019 ↗
B AlcoholFecundability drops with higher intake. Fan 2017 ↗
B Diet qualityMediterranean-diet adherence is linked to better IVF success. Karayiannis 2018 ↗
B Very high-intensity exerciseIn lean women it can disrupt ovulation; moderate activity is fine. Zhao 2022 ↗
C CaffeineLittle clear effect on conception; a pregnancy-safety guide, not egg damage. Lyngso 2017 ↗
Cycle regularityIrregular cycles can signal an ovulation issue — a doctor flag.
What we're honest about
Age is the master variable, and no lifestyle change reverses it. We show it, we never punish you for it, and we don't sell hope against it.
Supplements are deliberately left out. The oral-antioxidant evidence is rated low to "very low" quality, and popular pills like DHEA and melatonin show no live-birth benefit in randomized trials. We'd rather leave them out than sell them.
"Associated with," not "will improve." The best randomized trials improve health markers but haven't proven higher live-birth rates from lifestyle change alone (Legro 2022 ↗). Your signal shifts your odds; it doesn't guarantee an outcome.
Not medical advice. Gemel is educational and does not diagnose, treat, or predict conception. It's not a substitute for a clinician. If you've been trying to conceive for 12 months — or 6 months if the woman is 35 or older — or have known risk factors, see a doctor now.
References
Sharma R, et al. Cigarette smoking and semen quality: meta-analysis. Eur Urol 2016. PMID 27113031
Hoang-Thi A-P, et al. High ambient temperature and sperm parameters. Iran J Public Health 2022. PMID 35936544
Sermondade N, et al. BMI and sperm count. Hum Reprod Update 2013. PMID 23242914
Ricci E, et al. Semen quality and alcohol intake. RBMO 2017. PMID 28029592
Salas-Huetos A, et al. Dietary patterns and male fertility. Hum Reprod Update 2017. PMID 28333357
Ibanez-Perez J, et al. Physical activity and semen quality. Arch Gynecol Obstet 2019. DOI
Franasiak JM, et al. Aneuploidy with maternal age. Fertil Steril 2014. PMID 24355045
ASRM Practice Committee. Tobacco/marijuana use and infertility. Fertil Steril 2024. PMID 38284953
Sermondade N, et al. Female obesity and IVF live birth. Hum Reprod Update 2019. PMID 30941397
Fan D, et al. Female alcohol and fecundability. Sci Rep 2017. PMID 29062133
Karayiannis D, et al. Mediterranean diet and IVF. Hum Reprod 2018. PMID 29390108
Zhao F, et al. Physical activity, sleep and fertility. Front Public Health 2022. PMID 36408057
Lyngso J, et al. Coffee/caffeine and fertility. Clin Epidemiol 2017. PMID 29276412