Of course not, but pro-legalized abortion advocates sometimes make that desperate claim in an attempt to de-humanize the unborn. See Hookworms, Mosquitoes, and Embryos – Sifting Reality for a good analysis.
I actually like when pro-aborts use the “parasite” argument. It may get virtual high-five’s from other pro-aborts, but it is so transparently bad that it reveals to the middle-ground folks just how perverse the pro-abort thinking is. It is like a concession speech.
This doesn’t always work, but I typically point out that their view would mean that the baby could be fully delivered but still be attached via the umbilical cord and she would still be a “parasite.” Therefore, you could kill her any way you liked. They have usually painted themselves in a corner by that point and may actually agree that they’d be OK with that. Again, I’m glad to let the middle ground see that kind of immoral thinking. People who advance that argument are extremely unlikely to be moved from their position, but they aren’t the target audience of most pro-life reasoning.
Most pro-legalized abortion arguments — and especially ones like the “parasite” argument — are based on emotions and ignore the humanity of the unborn (human zygote, human fetus, etc.). They trade on sentiments how the woman (or child) will be impacted in the areas of poverty, education, love life, etc.
When doing pro-life reasoning training I always start by distinguishing between the psychological complexity of the abortion issue (financial, educational, family pressures, etc. issues are real and powerful and need to be addressed) and the moral simplicity of it (you shouldn’t kill innocent human beings for any of those reasons, regardless of how intense they are).