Falsus in uno, falsus in omnibus.
The foetus is truly human from the moment of conception, when egg and sperm unite to create a being will the full complement of human DNA.
That is science. But science has no moral significance, so to understand its implications for our values we must look elsewhere. Perhaps here:
Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me. (Matt xxv:40)
Oft thought, but ne’er so well expressed.