Accidental Pregnancy

I am curious how you have an accidental pregnancy in today’s day & age. Would love to hear some stores and gain a better understanding. I’m only talking about consensual sex. Only logical thing I can think of is not having access to birth control due to financial reasons or lack of sex education? I was luckily able to get an IUD when I was 18 for free through planned parenthood. This is a completely non-judgemental post I just want to be better informed on how these things happen!