The uterus undergoes a remarkable transformation during pregnancy, expanding from the size of a lemon to a watermelon over 40 weeks. It grows from 3 inches long and 1 ounce to supporting a full-term baby and weighing nearly 2 pounds. This elasticity allows it to safely house a growing fetus and shrink back after birth through uterine involution, occurring within six weeks postpartum. As it grows, the uterus rises from the pelvis to above the belly button by 20 weeks. Healthcare providers track this growth using fundal height to monitor healthy development. The uterus plays a vital role in pregnancy, whether carrying one baby or multiples.