I've worked in the birth field for about 4 years now. I've known all sorts of amazingly strong women who have birthed their babies in a variety of powerfully beautiful ways - including with the assistance of pain medications, epidurals and yes, even cesareans. The following is my opinion, based on what I've observed both personally and professionally.
Once upon a time, when I heard the term "natural childbirth", I envisioned the strongest of strong women - birthing their infants fearlessly, without the use of an epidural or pain medications. "Natural childbirth" sounded like such an unattainable goal to me, because quite frankly, I thought it was a term reserved for a select few of the bravest women in the world. I couldn't have been more wrong.
Here's what I've learned to be true. The mother who plans a completely intervention free childbirth, yet ends up with life threatening complications that earn her a surgical delivery is the bravest woman I know. The woman who is exhausted after being awake all night laboring and chooses to have an epidural so that she can rest before her child enters the world is the bravest woman I know. The woman who is terrified of the unknown, and delivers her baby after several doses of narcotics is the bravest woman I know. The woman who chooses to have a home water birth and screams her baby into the world is the bravest woman I know.
All of these mothers grew a tiny human (or two!) in their very own bodies! Each mother was so strong, so brave and worked amazingly hard to birth their children. Each and every one of these children entered the world through their mother's body. Shockingly natural, no?
Now, I challenge you to change the way you use the term "natural childbirth". What's more natural than a baby being born? I also encourage you to be careful with your words and actions, so that you never discount the magic and wonder of each mother's hard work and resulting miracle.