Do women always deliver on their due date?

Not really. I read that only 5 percent of women give birth when they think they will (their EDD). Most women -- about 80 percent -- deliver sometime between 37 and 42 weeks. About 11 percent deliver prematurely. It's also been observed that a first-time mom can look back at her mother's childbirth history. If her mother delivered one week past her due date, she is more apt to deliver one week past your her due date as well. http://www.parents.com/pregnancy/giving-birth/labor-and-delivery/the-truth-about-due-dates/