This is a motte and bailey argument.
The motte is that “murder, when defined as the killing of a human being after birth, is a bad thing.”
The bailey is that “murder, when defined as the killing of any human life whether before or after birth, is a bad thing.”
The first is intuitively obvious. The second is not. You’re just using the standard pro-life tactic of exploiting the intuitive response to the word “murder” and then slightly redefining it to suit your argument. I’ll hear you when you actually make the argument.