Becoming fertile

So a question, I am 26, and in a loving and supportive relationship. We have become pregnant twice this year but because of the pandemtic, we have chosen to end them both as we are both in job fields that are unstable at the moment.

My question is, why have I suddenly become fertile?

I have been sexually active since I was 17 and I never used any protection and I never had a scare or any issues.

So my question is, why am I now becoming fertile?