Fetal growth refers to the development of a fetus during pregnancy, typically lasting about 40 weeks. This process is divided into three trimesters, with each trimester marked by significant changes in size and organ development. By the end of the first trimester, the fetus is about 3 inches long and has formed essential organs. During the second trimester, the fetus grows rapidly, reaching around 12 inches by the end of this period. In the final trimester, the fetus continues to gain weight and develop, preparing for birth. Proper nutrition and prenatal care are crucial for healthy fetal growth throughout pregnancy.