Starting new jobs

Just wondering if anyone has ever felt unsure about your nursing capabilities when starting a new job or an area that you've never worked before. I've done Geriatrics for 10 years, and had worked for homecare for two. I would like to try something more challenging, but am afraid to do so. I have this fear that I wouldn't be able to handle something. I've always wanted to do OB, but am nervous about it. What if a baby dies or something really bothers me. I have this fear I would have to leave the room, and would embarass myself. Has anyone felt insecure in this way? Am I crazy?