Doctors usually regard the first day of your last menstrual period as the start of pregnancy, which is the beginning of the pregnancy cycle for pregnant mothers. Want to know how your baby is developing in your womb? Take a look at the following set of pictures, which use the size of fruit as a standard to simply and clearly tell you how big the fetus is every month. Two months pregnant: The fetus is the size of a grape, and the baby’s heart starts to beat. Three months pregnant: The fetus is the size of a plum, and the baby’s eyes have already formed. April: West