Whether abortions are in the scope of practice for a midwife would depend on the laws and regulations in your state.
As a midwife, you have the ability to be an independent practitioner. That means you get to be the boss of your practice. You decide what services you will and will not offer. If you don't want to offer abortions, then you don't have to. Midwives are not the same as a Nurse Practitioner, and I think you may be confusing the two. As a midwife, you would be referred patients who are pregnant and want their primary provider drink their pregnancy to be a midwife. You would follow the patient through the pregnancy, delivery, and the post partum period. It makes sense that patients would come to you when they want to have a healthy pregnancy. A Women's Health Nurse Practitioner would care for women in all stages of life, but not during pregnancy/delivery. If the patient wanted an abortion, she would not be referred to a midwife, but would instead see her general practitioner or go to an abortion clinic.
But as with any ethically controversial matter, you should be aware of your personal bias in these areas and make sure that you can counsel and refer your patients in a nonjudgmental way.
Please know that a midwife is not a nursing specialty, like a pediatric nurse. You cannot graduate from nursing school
and specialize in midwifery. To become a midwife you need several years of graduate level education and training, in addition to your RN license. Many Certified Nurse Midwife programs will require 1-2+ years of RN experience in an OB-GYN related field before you can enter the program.
Finally, it's nice that you have an idea of where you might like to work. However, remember that you haven't even entered nursing school yet. The reality of the nursing profession is likely far different than what you currently imagine. You might start taking nursing classes and clinicals and realize that you really don't like pediatric nursing, but find a strong interest in areas that you never considered (or never knew existed) before. In nursing school, you have to learn how to take care of all different kinds of patients. The majority of your classes and clinicals will focus on adults, and a small portion will involve peds and maternity. You can specialize after you graduate from nursing school and find a job- not before you start nursing school. Keep your mind and options open during your schooling.
P.S. A nurse that works with cancer patients in an oncology nurse. There are pediatric oncology positions, but most often pediatric cancer patients are taken care of on the general pediatrics floor.