The first trimester of pregnancy typically lasts from the first day of the last menstrual period up to the end of the 13th week, or about 12 to 13 weeks in duration
. This period marks the beginning of pregnancy and is crucial for fetal development, during which the embryo develops into a fetus with all major organs and body systems forming
. The first trimester generally covers the first three months of pregnancy and is characterized by significant physical and hormonal changes in the mother
