week 1
week2
week3
week4
week5
The "weeks" refer to embryonic development and differ from clinical weeks (shown in brackets, from the first day of the Last Menstrual Period, LMP or GA)The "stages" refer to Carnegie stages of development.The "timing" refers to days from fertilization or post conception age (PC), not the clinical or gestational age (GA) calculated from LMP (add 2 weeks).The dates and staging are also "ideal", and there is significant biological variability in the general timing of events.Week 1 to Week 8 are considered the embryonic period of development.Week 9 to week 37 or birth are considered the fetal period of development.The first month after birth is the neonatal period of development.
