Census count is irrelevant. If the next census included pre-borns, I doubt that would change your mind one iota. People may not know they are pregnant when they take the census, or conversely, may not be aware of carrying more than one child. Regardless, the benchmark placed is just that, a benchmark. Has no bearing on civil rights.
Actually, here's one I can answer for you. I was a census enumerator in 2000 and 2010. (I passed on 2020 because I didn't need the extra money and Covid). We had very specific rules on counting babies. If a baby was born after April 30, it was counted. If it was born after April 30, it wasn't.
I actually had a woman who I called on with her newborn, and had to very politely tell her that her baby born on May 3rd couldn't be counted in 2010, but we'd be sure to get her on 2020's census.
Tax deduction status is irrelevant. If tax deduction status was changed to include pre-borns, I doubt that would change your mind one iota. Tax deduction status has no bearing on civil rights.
Actually, this is the problem. Once you've given personhood status to fetuses, it doesn't stop with abortion.
We've already seen fetal personhood laws used to persecute women who've had miscarriages. Look up Purvi Patel and Bei Bei Shuai. It's very enlightening... no, wait, I mean horrifying what was done to these women.
Purvi Patel - Wikipedia
en.wikipedia.org
Bei Bei Shuai - Wikipedia
en.wikipedia.org
Please note that these abuses started with immigrant women of color.
Every miscarriage would have to be investigated as a potential homicide.
Women could be prosecuted for assault for smoking or drinking or even eating the wrong foods during pregnancy.
My toenail has Human DNA. It doesn't make it a person.What species are fetuses? What does the DNA evidence say?