In what trimester does the majority of fetal organ development occur?

The majority of fetal organ development occurs during the first trimester. This critical period spans from conception through the 12th week of pregnancy, during which the foundational structures and organs of the fetus begin to form.

During the first trimester, major developments take place, including the formation of the heart, brain, spinal cord, and the basic structure of other organs. By the end of this trimester, the embryo has developed into a fetus and has established the rudimentary systems necessary for subsequent growth and maturation.

In later trimesters, while further growth and refinement of these organs occur, the foundational development had already been established in the first trimester. Thus, understanding the importance of the first trimester is vital for recognizing the crucial developmental milestones of fetal growth.