How will I know how many weeks and months pregnant I am?

It's calculated counting from the first day of your last menstrual period (LMP) instead of the day you conceived. By convention, all pregnancy are given a 40 week duration, from the LMP to the EDD (Expected Date of Delivery) It is normal to go into labour after 37weeks. Most women will deliver by 40 weeks. A few remain pregnant after 40 weeks and may then need to be induced to go into labour.