Implantation: Process, Timing and Early Pregnancy

Implantation is the process by which the blastocyst embeds into the receptive endometrium, occurring approximately 6–10 days after fertilization (days 20–24 of a 28-day cycle — the implantation window). Successful implantation requires a properly developed blastocyst, a receptive endometrium (progesterone-primed), and appropriate molecular dialogue between embryo and endometrium.