Pregnant on purpose and by accident.
The last two times I have been pregnant (ended in miscarriage) have been (mostly) on purpose. Prior to that, I was (to my knowledge) accidentally pregnant as a teen, though very happy, it also ended in miscarriage.
With baby #2 my husband and I tried for upwards of 3.5 years and I was taking fertility supplements to conceive, so definitely planned.
Baby #3 was directly after the miscarriage. Though it was a blessing to conceive, my husband and I both expected that it would take more time and more fertility supplements to conceive, and we were not going to 'try' until after I had one normal cycle. Lo and behold that normal cycle did not come because I became pregnant again without even a cycle in between. Unfortunately, my tests turned negative a couple days later and bleeding arrived. So baby #3 wasn't expected or planned, but not prevented either.
As of now, we are not preventing, but I have not yet resumed fertility supplements.