I have done extensive research about sterilization. Coming upon a third cesarian delivery, I was told my risks of rupture increase with each surgery and pregnancy. (not necessarily ture, but none the less...) I was faced with the decision to rely solely on Natural Family Planning or chose tubal ligation or another form of Birth Control. Well, as a practicing Catholic, I wanted to be certain that I was not going against the church's teachings. And I wanted to know what those teachings were, and how they applied to my situation. Happily I found all the answers I was looking for, and am pleased to know that NFP is not only the only choice, but the best choice for the heath of my marriage and my body. I hope you will all take a look at the articles I found to help reassure yourself in this decision. It's not just a Catholic choice, it's a profound lifestyle that ensures the quality of your relationship with your spouse. And it's a true testament to respecting all life.
Father Saunders Article: Sterlization as Contraception - http://www.catholicculture.org/library/view.cfm?recnum=6364
(this was the best article, describing that because my organs are functioning healthy and are not "diseased" that would risk my life - it is a mortal sin to have them removed or altered. The only acception was if I had a hysterectomy because of rupture or cancer/disease which resulted in sterilization. But not acceptable to remove or alter due to personal choice to sterilize.)
Natural Family Planning:
Catholic Viewpoint on Birth Control:
Married Couples Who Intentionally Chose Sterilization For Contraceptive Purposes And Lasting Repentance : http://www.catholic.org/featured/headline.php?ID=655
A final resource for all couples: