The only time your opinion on abortion is of any weight or relevance is when you are pregnant and do not want to be. Therefore, if you are a man, your opinion on abortion is completely unimportant and irrelevant to the rest of the world. If you have impregnated a woman, then you may want to discuss the issue of whether or not the pregnancy continues, and she may be happy to discuss it with you. Or she may tell you to fuck off. Either way, the decision is hers and not yours. Because she is not your property.
By the way, as far as the law is concerned when it comes to parents who are not in a couple relationship and not on speaking terms, even though the woman is intending to carry the pregnancy to term, the man has no rights whatsoever. He can't go to antenatal appointments, police her behaviour, attend the birth, unless she lets him. If he wants to have contact with his baby against the mother's wishes, he has no rights at all until the baby is born. (Yes, technically, the man has no rights anyway, the rights in question are those of the child to see his/her father). I am entirely in favour of this.
So personhood is conferred at birth. This seems to be the only sensible way of looking at it. Birth is indisputable. Stuff about how many weeks pg a woman is, well, you can';t be sure of exact dates, some very premature (wanted) babies live and thrive and, a few years down the line, are no different to full term babies, some less premature but still premature babies die shortly after birth, etc. No guarantees, no matter what.
But everyone who is actively and vehemently opposed to abortion is really all about hating women. Well-meaning twerps who think late abortion is an unpleasant thing and there 'ought to be a cut off date' are just well-meaning twerps. Just take a look at the more and more alarming laws being enacted in the US, to restrict women's access to contraception, sex education, to criminalize them for drinking or taking drugs or doing risky jobs even if they are not pregnant and don't wish to be - the whole anti-choice agenda is about men desperate to own and control women and reduce them to a subhuman status of 'walking incubator.'