How to stop getting mail from Life Dynamics Incorporated (anti-abortion group)?

For the past few months I've been getting mail from Life Dynamics Incorporated/Mark Crutcher, an anti-abortion group. I have no idea how they got my information or why they're sending me letters (they've also sent me anti abortion pins). Thing is, I am pregnant right now and about to have a baby, but before this baby I was pregnant some time ago and had gotten an abortion, so all of these letters make me feel uncomfortable. I've gone on their website but don't see anything about unsubscribing from letters, and the only phone number I see is to help donate for their cause. Has anyone else received mail from these people, and how did you get them to stop sending you stuff? Thanks.