What important developments will the foetus undergo in the first trimester?

Differentiation occurs, which is when the cells have finished dividing and take on particular roles, such as a liver cell, or brain cell. The spine forms The heart begins to beat The baby fully forms and looks like a proper human The baby can yawn, swallow and suck his or her fingers The baby has fingernails and toenails Believe it or not, this all happens before the end of the first trimester!! I have added a link in the related links which I think will give you more information than I can