This question already has an answer here:
As the heading says, why would Voldemort want a child? I've got the following arguments against the matter:
Voldemort was planning for immortality, so he hardly would need an heir.
Thinking of an heir would be acknowledging the fact that he could die, something he always refused to do.
Even if Delphi was supposed to be a follower than an heir, why would Voldemort risk having a child when he had so many Death Eaters?
Voldemort has no family sentiment(murdered his paternal relatives, got Morfin framed, denied that his mother was a Muggle,etc) so what would make him think that a child of his would be useful or special? I say this because many answers would say that Voldemort wanted a new right-hand man, but Voldemort, who never trusted or got attached to anyone, was unlikely to make an exception for his child.
If Voldemort did want a right-hand man, could be not put it off till he was absolutely sure he had won? After all, he still had to kill off Harry, his first priority, his obsession. Surely he would think of a child after "settling down" into his rule, rather than go for it in the middle of a war?
Voldemort always wanted to be the sole object of worship for his followers. Surely having a child had the possibility of creating a new leader for his followers ( for example: "Why follow Voldy, he's so harsh, let's back Delphi in a coup, she's liberal"). It could cause unnecessary undermining of his authority and create secondary centres of power, while Voldemort likes keeping things centralized around himself.
If all he wanted was a capable assistant, why would he go for a child? Pardon the similie, but isn't it like commissioning a $200000 lawnmower... to mow the lawn? Too much effort for a simple matter.
Finally, he, the lone wolf, would prefer to operate alone. Surely having a child would elevate both the child and its mother to a higher level than master-servant? Wouldn't he foresee the unnecessary complications of placing them closer to himself, at least in others' view? (For example: "Bella is his favorite, grumble grumble...")
P.S.: Despite all my arguments, I welcome any answer that is logical and addresses the questions I raise.