I think there is data on it. Back in school I remember looking at the population pyramid. It’s a visualization of the number of men and women (x-axis, going both left and right) per birthyear (y-axis). In ye olden days, that formed a triangle. Many babies at the bottom, fewer olds at the top. You could tell a lot from the shape this took. You’d get dents on the male side that will correspond with armed conflicts, like the world wars. And then in the 1960s the pyramid with war chips in it massively narrows. At least in countries where the pill became readily available. It turned the pyramid into a tree with a big head at the top and a wide but thinner stem growing under it. I suspect now 80 years later we’re at a much narrower elongated triangle shape again. So you can probably count the shift in numbers there and put a number on “prevented accidents.” But you would have to account for other factors as well, improvements in medicine, vaccinations, etc.

Were all births accidental? That’s a question you could only ask in hindsight. Humans have always looked for ways you prevent conception because we like to party but without reliable success. It’s only in the second half of the last century that we have come up with measures that the Catholic church really doesn’t approve of. Before that, children weren’t really planned in today’s sense. They just happened. They were expected to happen. And with most women being relegated to raising them and running the household, there wasn’t much else they could do. The concept that a wife could be raped by her husband is sadly fairly new. The patriarchy was strong. Abortion was a gamble and many women died from bad jobs of them. Most of the time, if she got pregnant, the decision was made, end of story. If you weren’t married yet, shotgun wedding. That’s how it went until we developed contraception that actually works. I wouldn’t call any kids before that accidental.

Sure, you could remain abstinent. But we like to party.