Stress
Being on call means a twenty-four-hour day once a week and one weekend a month. If you work at a hospital, that means juggling a mother in prolonged labor with patients showing up in the ER. You'll have a load of ethical dilemmas to consider on a regular basis and, most of all, you can never, ever, no matter how slippery and wiggly it is, drop the baby. That's super stressful for just about everyone involved.
Doctors are stressing a lot more about one thing: the amount of time they spend with patients. Insurance companies hold the purse strings and they aren't about to loosen their grip. Seeing up to 150 patients a week means spending less than twenty minutes with each one.
You'll have to find a way to cram all your experience and knowledge into a very small window of time. Make sure you've got your patient's attention and let her know you've got her best interests at heart. Being able to communicate with and reassure her will make you both feel a lot better.