From the beginning of Oedipus Rex there are prophecies that insist the ultimate fate of Oedipus. Although these prophecies are excruciating, they are prophecies that in the end all come, true and lead to the destruction of Oedipus Rex. This proves that man has no power to stop what has been destined to happen. Iokaste through love and concern for her son tries to prevent these awful prophecies from happening, but in the end she is the ultimate cause of Oedipus Rex's grief and downfall.
In life there is not one mother who wants to see there child suffer or die. Although this is a Greek play, even in the world that we live in today many people end the lives of children because they believe that it is better for them to be at rest than to suffer in life. Iokaste from the beginning of the play knew that her son was destined to kill his father. That is why from the time he was born, and she heard the prophecies she was determined to prevent her son from killing his father and marrying his mother. Iokaste must have felt that something like that would defy the mores of society at that time. This is why she was determined by any means necessary to make sure this did not happen. In sending her son to the servant to be killed Iokaste obviously had confidence that this would be the end of something that had not started yet. Of course by handing the baby to the servant Iokaste was already making her first big mistake. In that time a prophecy was a prophecy and for Iokaste to think that she could escape this, she was wrong. The only thing that she was doing was to furthermore make the prophecy be played out even worse then how it was supposed to be played out.
Iokaste throughout the play does not even realize what she has done. She does not realize that she is the one that put her son in all of his misery. For example when Oedipus says, Ah, what net has God been weaving for me? The Iokaste says Oedipus! Why does this trouble you?" This a very strange thing to say because naturally Iokaste should be feeling guilty for what she has done to her son, but instead in her head she doesn't even recognize the fact that it is her son that she once tried to get rid of.