Even before the most recent ads, organizations that masquerade as health services have advertised on transit, seemingly hoping to target younger and more vulnerable women. These organizations are explicit about their intentions to dissuade people from having abortions on their websites but do not provide this information on their bus ads, nor do they properly disclaim their bias.
I am deducing that the transit ads they refer to are the ones put up by www.signs4life.ca
I cannot see how they can claim that this ad is untruthful. More specifically, they claim that the statement is "unscientific".
I would say that their claim is the one that is in error. Ask any medical doctor, or even a second year med student, when does life begin and they will tell you life begins when the sperm fertilizes the egg. What else could possibly be the case?
As for the claim that the life may be human, but it is not yet a person, this is a philosophical statement and one that cannot be proved because it is a belief rather than a fact. The definition of personhood is a construct that we have developed but it really says nothing about whether a being is alive or not.
If someone wishes to defend abortion, go ahead and defend it. But please do not claim that the pro-life statement about when life begins is not scientific because that is simply untrue.