Work backward from pregnancy dating references to an approximate fertilization anchor with a reversible dating timeline.
01 / PURPOSE-SPECIFIC INPUTS
This estimates a fertilization anchor, not a known intercourse date. It cannot establish paternity or implantation timing.
02 / RESULT & INTERACTIVE INSPECTION
This calculation cannot establish paternity, confirm a known fertilization date or identify implantation timing. Clinical dating should guide care. Calendar estimates and any comparison are not averaged or treated as proof.
Inspected position: Oct 8, 2026. This is an illustrative timeline position, not a newly determined medical date.
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Choose a due date, LMP, clinical age or ART reference. Calculate the approximate fertilization anchor. Inspect the reverse timeline and the limits of intercourse-date inference. Read the worked explanation and scope alongside every result.
Work backward from pregnancy dating references to an approximate fertilization anchor with a reversible dating timeline. Interactive controls inspect the calculated model without silently changing submitted assumptions.
Pregnancy Conception Calculator inputs and calculations remain in browser memory. No external processing API receives entered dates, measurements, coefficients or financial values. Ordinary website page requests may still be logged. Clipboard access occurs only when you choose Copy Result.
For spontaneous pregnancy, the model works backward approximately 266 days from the entered or derived estimated due date. It is an approximate fertilization anchor, not an observed event.
No. Conventional gestational dating begins about fourteen days before the modeled fertilization anchor. The timeline labels the LMP-equivalent start separately.
No. The five days before the model anchor illustrate possible sperm survival before assumed ovulation/fertilization. The window is not a precise conception interval, confidence limit or proof about intercourse timing.
No. Calendar dating cannot establish paternity, an exact known fertilization event or implantation timing. Clinical dating should guide pregnancy care.
The transfer date and embryo age establish an ART-based dating anchor. Transfer is not fertilization, and a natural-cycle intercourse window is intentionally omitted.
The full reverse timeline connects the due date to the dating start and fertilization anchor. The focused view enlarges the nearby twenty-day span without changing the underlying entered reference or implying greater medical precision.