The argument almost everyone in the pro kill the child in the womb movement uses is they cannot sustain their life independently. It's a reason they believe, among many others, they have the right to kill their child. "It's my body, it's my choice" or "they are part of my body and I give them life, so therefore I can take out that life when I feel like it."
The problem with that argument and where it falls apart is when confronted with the reality that a 3 year old also cannot sustain his own life.
If you don't see the hypocrisy, I can't help you.