Fertilisation: Fusion of ovum and sperm on day 1
Morula: Solid ball of cells after 3 days
Blastocyst: Hollow ball of cells after 5 days
Trophoblast: Forms early embryo, fetal membranes, and placenta after 5-7 days
Embryo: Developing human from fertilisation to the 8th week of pregnancy
Fetus: Developing human from 9 weeks of pregnancy to birth
Neonate: Newborn baby from birth to 28 days old
Infant: baby or young child age less than 1 year