You're right, the reasons women have an unplanned pregnancy are entirely irrational, and irresponsible. The individual circumstances are infinite. Sometimes when women feel the most horny enough to have risky sex, is the time when pregnancy is going to occur.
The option should be a choice. It does no benefit to anyone to make it illegal. It doesn't save lives. Being pregnant, having a baby, doesnt make anyone accountable.
Also a lot of birth control methods work by triggering an 'abortion' in event the first defense fails. It makes the uterus inhospitable to a fertilized egg. Can't know for sure if that method has gone down inside the womans body. Dead baby? lol