Gestational age refers to the length of time a pregnancy has lasted, measured in weeks from the first day of a woman's last menstrual period (LMP). It helps healthcare providers assess the development of the fetus and determine the expected due date, which is typically around 40 weeks. Healthcare professionals often use ultrasound imaging to confirm gestational age, especially if the LMP is uncertain. Understanding gestational age is crucial for monitoring the health of both the mother and the baby, as it influences decisions regarding prenatal care and delivery.