When does pregnancy begin?
Medical and scientific experts agree that pregnancy begins with implantation. It happens several days after fertilization when the developing pre-embryo is implanted in the wall of the uterus. Implantation begins the release of hormones that are necessary to support a pregnancy.
In short, a woman is not pregnant until the developing pre-embryo is attached to her and gets nutrients from her. For example, a fertilized egg in a petri dish does not represent a pregnancy.
To learn more, check out our animation: How Pregnancy Happens (Flash).
