Here is why God can't hate any man or unborn child.
First God is good and infinitely so this means he desires the good all all creatures or he is not good at all.
For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. (NIV John 3:16)
This is good, and pleases God our Savior, 4 who wants all people to be saved and to come to a knowledge of the truth. 5 For there is one God and one mediator between God and mankind, the man Christ Jesus, 6 who gave himself as a ransom for all people. (1 Timothy 2:3-6)
Second, God command us to love his enemies, if he did not love them then He has not commanded us to be like Him.
Third Jesus loved everyone, and Jesus was God.
Fourth, God command us not to show partiality, that is favor one man over another, because God does not show partiality, that is he does not love one man more than another. (1 Timothy 5:21)
Now the meaning of a verse like 'God loved Jacob but hated Esau' as used in Romans, simply means that before Jacob or Esau had any chance to 'will anything' or perform any 'good work' that could obtain favor, their fates were sealed and predetermined. Therefore, this hatred is not sinful hatred but showing God's absolute preference for Jacob according to election. For although God loves all men, only those who believe in Christ enter into God's grace and become objects of that love. Love that is allowed to be applied and made real is a higher love according to election and comparably without it, it is like the strong disfavor of even hate. The same strong difference of emotion is called hate in Luke 14:26 where he are told to 'hate'. Therefore, to speculate that this hatred is the evil hatred of 'wishing bad things towards another', is to imagine God is sinful?! What is strange is that many very strong Christians put their brains into ptrezels and actually suppose this theologically!?
In reality, I do not think this idea of God only loving the elect rises more than a meaningless philosophical conjecture. A human can't really believe God hates people without having an emotional breakdown. There is a difference between philosophical conjectures and real beliefs even when there are strenuously defended. Calvin over speculated this way and even my favorite theologian argued this way in the 1700s. I forgive them because they were fighting against vile Arminianism and good men often over-reach when defending the truth, in this case, of God's election.
My fellow Calvinists may accuse me of being non Calvinistic and shocked at my fully support God's boundless love for all men, but I say just because I am a Calvinist does not mean I follow every single thought and conjecture of Calvin as though he was a God. God forbid that I would deny God's love, no matter who speculated against it. What I beleive is absolute eternal election of those to salvation and those to hell, yet at the same time beleive in God's love for all men and think it is unbiblical to deny it. It appears that I contradict myself but so did Luther so I am in good company.
Luther had a more mature view about predestination than Calvin did, simply put. Calvin was less humble in my view and could not resist being a precocious school man and speculating to far. Luther was more humble and knew when not to speculate.
Here is Luther's typical attitude about it:
He [Martin Luther] spoke at length about the idle people who occupy themselves with disputation about predestination beyond the limits of Scripture. It is most ungodly and dangerous business to abandon the certain and revealed will of God in order to search into the hidden mysteries of God. (Luther's Works Vol 54, P249)
In fact Luther argues that the phrases used by the Bible oppose speculations about it and insists that we believe in contradictions allowing them to be resolved in a mystery beyond our comprehension:
The Hebrew reads this way: “I will show mercy on whom I will show mercy, and I will be gracious to whom I will be gracious” (Ex. 33:19). This is said in an indefinite sense as it were and as if He were offering mercy by chance, without reference to predestination. In the same way He also says in Ex. 3:14: “I am who I am,” or “I shall be who I shall be.”
He seems by these words to be rebuffing those who are anxious and curious about the predestination of themselves or of others, as if to drive them away from thoughts and questions about predestination. As the common saying goes: to whom it comes it comes, and whom it hits it hits. It is as if He were saying: “No one will know to whom I will be merciful and to whom I will be gracious, nor can anyone be certain about it because of his merits or his works or anything else.” (He [Martin Luther] spoke at length about the idle people who occupy themselves with disputation about predestination beyond the limits of Scripture. It is most ungodly and dangerous business to abandon the certain and revealed will of God in order to search into the hidden mysteries of God. (Luther's Works Vol 25, p386)
In Luther's work on the will, where he argues we do not have free will in terms of our being saved, but that only God's grace can save a man, the introduction says:
Yet Luther acknowledges that man possesses a capacity for response to God’s grace which other creatures do not (see p. 67); and elsewhere he can explain why God elects this man and not that by saying: “This difference is to be ascribed to man, not to the will of God, for the promises of God are universal. He will have all men to be saved. Hence it is not the fault of our Lord God, who promises salvation, but it is our fault if we are unwilling to believe it”. (Introduction to Luther's Work 'The Bondage of the Will', LW Volume 33)
To confirm Luther's view against God's love for only some:
He tells us to pray for all men, because such a prayer for men is acceptable, even if they are wicked. The grace of God is one and the same, even for the faithless. We must therefore pray not only for the faithful but for all men. That prayer offered for them is both heard and pleasing, because He wants it so and desires to save all men. (Luther's Works Vol 28, p261)
Just to show not every Calvinist sided with Calvin on this point, but rather was more along the lines of Luther, here is another famous Calvinist.
Why does God hate any man? I defy anyone to give any answer but this, because that man deserves it; no reply but that can ever be true. There are some who answer, divine sovereignty; but I challenge them to look that doctrine in the face. Do you believe that God created man and arbitrarily, sovereignly—it is the same thing—created that man, with no other intention, than that of damning him? Made him, and yet, for no other reason than that of destroying him for ever? Well, if you can believe it, I pity you, that is all I can say: you deserve pity, that you should think so meanly of God, whose mercy endureth for ever. (A Sermon (No. 241) January 16th, 1859, by the REV. C. H. Spurgeon)
So does God hate an unborn child, as in wish them harm, of course God alone could NEVER as He LOVES all unborn children with infinite love.