Human Growth and Development / Unit 2 HGD 0180 short lesson, about 20 seconds
Trimesters and Periods
Captions available
The idea
Pregnancy is counted in three trimesters, but prenatal development runs through three periods of its own: germinal, embryonic and fetal.
In practice
One pregnancy on two timelines: trimesters for the calendar, periods for development.
Where people slip
The two do not line up. The germinal and embryonic periods are both over well before the first trimester ends.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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