What causes cervical polyps?   would you suggest removing if pregnant? Or taking a biopsy?

HPV and no. Most cervical polyps are caused by some strain of hpv. It is generally not recommended you do anything with them while pregnant, for fear of inducing a miscarriage.
UNKNOWN. I would not remove a cervical polyp during pregnancy if it was not bleeding. It should be removed after pregnancy if still present. Most cervical polyps are benign.