And then let's discuss the birth period, the birth process. So the human gestation period begins with the last menstrual cycle of that woman before she undergoes sexual intercourse and then ends with the birth of that fetus. And normally, it's about 280 days which is equivalent to 40 weeks. Now, the human gestation period can be broken down into three sections, into three stages or three trimesters. So we have trimester one, we have the second trimester and we have the third trimester. And within each one of these trimesters, something important takes place as we'll see in just a moment.