We could say that before conception, everyone agrees there is no child, and at birth, everyone agrees there is a child, so there is maybe a "spectrum" between "idea of a child" and "an actual he/she".
Your use of the wording "much more" sort of supports this "probability distribution function" idea of what a child is, and it seems like a helpful philosophical framing of this difficult and important question.
What I would say, though, is that if society is going to pick a point along that spectrum to base policy decisions on, then there is an imbalance between the risks of placing that point too early versus too late.
Too early means that some women's decisions will be unreasonably restricted, whereas too late means that some human being's lives will be unreasonably terminated.
The philosophically humble thing to do under such uncertainty would therefore be to err on the side of an earlier point, and in fact the earliest point possible, lest future generations look back on us like the slave owners or eugenicists of previous centuries.
The child doesn't, though, and, if you'll excuse my frankness, I think the abortion affects his/her future the most out of all the parties involved.