Predictive Bioharmonics: Preimplantation Embryo–Endometrium Exact Timing Algorithm (PEETA)

Implantation failure in IVF frequently occurs despite good embryo morphology, normal genetics, and apparently receptive endometrium, indicating an unmeasured constraint related to exact temporal compatibility. This document introduces the Preimplantation Embryo–Endometrium Exact Timing Algorithm (PEETA), a deterministic phase-locking algorithm that computes the precise temporal window in which an embryo and an endometrium can dynamically couple for implantation within a given IVF cycle. PEETA does not predict pregnancy, assign probabilities, rank embryos, infer endometrial receptivity, or introduce new biological measurements. Instead, it determines whether exact temporal phase alignment between embryo development and endometrial readiness is dynamically possible and, if so, returns a bounded timing window using only early embryo division timings (t2–t4) and cycle timing as an endometrial phase proxy. If no temporal overlap exists, implantation is classified as dynamically impossible in that cycle, independent of embryo or endometrial quality. PEETA is non-invasive, fully deterministic, retrospectively testable, and applicable prospectively as a decision-support algorithm for exact IVF transfer timing.