Essays / Writiting a Rogerian Analysis Essay (about abortion) [2]

I understand that you're suppose to understand both sides of an argument but be able to promote one side to refute your own.
I'm just not sure how to start off by defining the topic.
My topic is on abortion.
right now all i have is
"Abortion is a medical procedure that results in the end of a pregnancy by removing the fetus or embryo from the uterus."
I need to write in MLA format. is it okay if i cite something in the first paragraph?

please help, I'm stuck on that one sentence!