I have a few questions

Hey ladies

I have a question. I was reading about the process of becoming pregnant. And it was saying that our body knows when we are going to become pregnant even before the implantation even have occurred. Is that why we feel some of those symptoms? Have you read that before? I know it is difficult to know between pregnancy symptoms and period symptoms. But it also said our body knows the difference. Funny that strange because I feel like every cycle I get symptoms even feeling both symptoms. What about you?