Spotting before period ?

For all the ladies who spot before periods ,

I have two questions :

1) what are the resons for it ?Is it low progesterone ?

2) When and if you got your BFP ,Did you spot even in that cycle before hand or not ?

It is really important for me ?

Many thanks in advance ,Really appreciate your reaponses ?

Kind Regards

Anuja Shukla