When does a blastocyst attach to the uterine lining?

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A blastocyst typically attaches to the uterine lining (the endometrium) between 6 and 10 days after fertilization.1

Prior to this attachment, the uterus must be suitably prepared by ovarian hormones, particularly progesterone, which increases the blood supply and nutrient secretions in the uterine wall to support the developing embryo. Once the blastocyst makes contact, it adheres to the lining and begins the process of implantation, during which it erodes the surface of the endometrium to embed itself within the deeper tissue. By the 11th day after fertilization, the blastocyst is typically completely embedded within the uterine lining.1234