From the impregnation to the nidation of the blastocyst into the uterus, ca. 5 days pass by, then it takes 10-11 days until the embryo forms. After overall 8 weeks (completion of the organogenesis), the embryo becomes a fetus, whose organs and tissues have to furtherly develop and differentiate.
During the embryonal phase / the organogenesis, the unborn is most prone to deformities.
