It IS the measurement for the length of gestation. That is a fact. Trimesters are names for different times during the pregnancy, but gestational age is the length OF the pregnancy.<quoted text>
Gestational age begins before gestation, and continues after gestation, which obviously is not the length of gestation. The length of gestation is measured with trimesters. Gestational age is an approximation of the baby's age. Our age begins with fertilization, and neither the gestational age nor the calendar age of infants is ever 0.
Our age begins at birth, not before. On the day we were born, our age was 0, NOT 36 weeks. That is another fact.