Freud said that the Greek play Oedipus Rex was effective because it dealt with a basic human instinct. A boy unconsciously wishes to murder his father and marry his mother. The play Medea also deals with a basic human emotion which might be called the Medea complex. Not all women but some women will conceive a hatred for their own children if they are exploited and abandoned by the man who fathered them. They may have actually had the children in the hope of tying the man to them with financial, emotional, legal, and ethical bonds. Medea is an extreme case. Many women are more likely to lose their motherly affection and may resort to verbal abuse but not go to the extreme of committing murder. A good example of a woman who cannot love her son because she despises her husband is to be found in D. H. Lawrences's well-known story "The Rocking-Horse Winner." (Another, more trivial, example is to be found in Roald Dahl's short story "Lamb to the Slaughter." The husband, like Jason, knows he is being a complete heel in abandoning his wife when she is six months pregnant. She takes her outrage on him directly--but if he were not avaiable, she might have taken in out on the child when it was born.)
It is not at all uncommon for women to be deserted by their husbands and then left to raise his children on their own. A divorced woman with a couple of small children will typically have an extremely difficult time in finding another husband, and without a man to at least help provide for the children, she is stuck with the drudgery of providing for them and acting as both mother and father. It is not unusual for some women in this common situation to feel some dislike for her own children--especially if the children happen to be boys, as was the case with Medea.
In the story of Medea, she went to unusual lengths to help Jason because of her deep love for him. When they were being pursued at sea she actually killed her own brother and cut his body into pieces and scattered them overboard, thereby forcing the pursuers to stop to collect the body parts and allow Jason and Medea time to make their escape. Jason is treating her outrageously now that he has an opportunity to marry a young and beautiful princess and eventually become king. Medea's love for him has turned to hatred. (This in itself is a common phenomenon. Love can turn to hatred, and often does.) "Hell hath no fury like a woman scorned." And she is stuck with raising his two children--who happen to be boys and therefore resemble their father and serve as a constant reminder of their perfidious father.