Last updated: 24 April 2026
This page explains how fertifacts™ arrives at the numbers you see on the results screen and in your research summary. Our goal is transparency: every figure is a pointer into published, peer-reviewed literature, national registry data, or current fertility-society guidance. The tool is a curated literature review, not a clinical assessment.
You enter your age and a few general lifestyle inputs. The displayed figures on the results screen and in the charts are pure age-based population statistics, pulled from published sources for four scenarios: natural conception probability within 12 months, per-cycle In Vitro Fertilization (IVF) live-birth rate, cumulative live-birth probability from a given number of frozen eggs, and per-cycle donor-egg live-birth rate. The lifestyle inputs you provide (BMI category, smoking status, cycle regularity, self-reported stress) do not shift the numbers shown on the charts. They are used only to personalize the written discussion in your research summary PDF, where we describe, in a decreases-only direction, how the peer-reviewed literature has associated those inputs with reduced fertility outcomes.
The tool does not measure ovarian reserve, anatomical factors, sperm quality, tubal patency, uterine receptivity, or any other individual-level factor that a clinician would assess. It does not diagnose infertility. It does not predict your personal outcome. It does not recommend treatment.
Section 1Used on the "Natural conception" box and chart. The age-probability curve is compiled from multiple longitudinal and prospective cohort studies that measure the cumulative probability of pregnancy within 12 cycles of unprotected intercourse across adult age groups, cross-referenced with current fertility-society guidance.
Used on the "In Vitro Fertilization (IVF)" box and chart. Live-birth rates per retrieval cycle are compiled from the two largest publicly available national registries and cross-referenced with current practice-committee guidance from the American and European fertility societies. We present rates as the probability of at least one live birth from a single retrieval cycle (cumulative across the fresh transfer and any subsequent frozen-embryo transfers linked to that retrieval).
Used on the "Egg freezing" box and chart. The per-egg live-birth probability by age is taken from the largest published retrospective analysis of vitrified oocytes and cross-checked against US registry data. From the per-egg probability we compute the cumulative probability of at least one live birth when N eggs are thawed, using the formula 1 - (1 - p)N, where p is the age-specific per-egg live-birth probability. The chart shows this for N = 10, 15, 20, and 25 eggs. Recommended egg-target ranges are based on published guidance on the number of mature oocytes required for a reasonable probability of at least one live birth at a given age.
Used on the "Donor eggs" comparison. Donor-egg live-birth rates are largely independent of the recipient's age and depend primarily on the donor's age and clinic practices. Our figures are compiled from SART registry donor-cycle outcome tables and cross-referenced with the most recent ASRM and ESHRE practice guidance.
The displayed percentages on the results page are not adjusted based on your lifestyle inputs. They are age-based cohort figures only. Your lifestyle answers (BMI category, smoking status, cycle regularity, self-reported stress) are used exclusively to personalize the written discussion in the research summary PDF. That discussion is decreases-only: it describes how the peer-reviewed literature has associated each factor with reduced fertility outcomes where the evidence supports it, and flags where the evidence is weaker. We do not report "boosts" from favorable inputs because the literature does not support reliable upward adjustments at an individual level. The sources below are what the written discussion draws on.
We use three broad categories (underweight, normal, overweight / obese). BMI at extremes (under 18.5, over 30) is associated with reduced fecundability and reduced IVF success in multiple large cohort studies.
Current smoking is associated with earlier menopause and reduced fecundability in multiple meta-analyses. Former smokers show intermediate risk that declines with time since quitting. The current ASRM committee opinion also discusses marijuana use alongside tobacco.
Irregular cycles are associated with reduced fecundability, largely through anovulatory cycles and conditions such as PCOS. The written discussion flags this where the user self-reports slightly irregular or clearly irregular cycles.
The evidence base for stress as an independent fertility factor is mixed. High chronic stress has biological plausibility through HPA-axis effects on ovulation, but the causal effect size in healthy women is modest. The research summary flags this with appropriate caveats rather than assigning a quantitative adjustment.
Your research summary is a personalized PDF that pulls together the age-based population figures relevant to your age bracket, plain-language explanations of what the cited studies report, a lifestyle section that discusses modifiable factors supported by peer-reviewed research (framed as reductions where the literature supports them), a supplement section that summarizes current evidence on commonly discussed ingredients (including where the evidence is weak), and a list of discussion points you may want to raise at your next doctor visit. The PDF is explicitly educational. It does not diagnose, prescribe, or predict an individual outcome.
CaveatsTreat the numbers as a starting point for an informed conversation with a reproductive endocrinologist, not as a decision in themselves. If you are considering In Vitro Fertilization (IVF), egg freezing, or any fertility intervention, please consult a licensed clinician who can order appropriate tests and evaluate your full clinical picture.
FeedbackIf you believe any of the cited figures are out of date or misrepresented, please write to hello@drmaxmulke.com. We review this methodology page periodically and welcome corrections from clinicians and researchers.
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