A friend recently asked the following:
So, what method of NFP do you use? Particularly while breastfeeding? (I am 4 months pregnant, and have an 8 month old, so you can do the math to see that BFing doesn't do anything to suppress my fertility, but it does make my cycle difficult to figure out, and not even "trackable" using a fertility monitor...)
Okay, so NFP. I'm not going to bore you with the details of WHY we don't use artificial contraception, because that's an entirely separate discussion. I'll simply say that we follow historic Catholic Church teaching on the matter. (And the reason we follow Church teaching is a REALLY separate discussion!)
I will also say that we do not personally look to NFP as a SUBSTITUTE for artifical contraception. We desire for our marriage to be open to life, for children to be an organic part of our union together. Check out Cormac Burke's Covenanted Happiness for an aMAzing perspective on marriage, sexuality and children. (It is, sadly, out of print, but if you can't find it at your library you can read the book in its entirety online, at that link.)
So. If there IS something we prayerfully and mutually deem to be a "grave reason" for delaying the conception of a child, then we simply abstain during the time of the month when I am most fertile. We've honestly rarely utilized NFP over the course of our marriage. I will tell you though that a few months ago my cycle returned (I'm still occasionally breastfeeding my youngest), and we decided to use NFP as we wait for our girls to come home. It's something I think and pray about a lot, because on the one hand it seems unwise to conceive a child with two adoptions on the horizon. On the other hand, I've chosen the vocation of marriage and that involves the bearing of children. I take that seriously. It's all very humbling.
And here's the funny thing. Are you ready for this?
I was literally about to tell you that I don't really use a method. I was about to oh-so-vaguely say that I, um, pay attention to my body's symptoms to predict ovulation. But I just now read something that said I AM apparently using a sytem: the Creighton Model.
Who knew I was actually being all official and following something scientific?
We keep track of my cycle on a spreadsheet that Kevin rigged up (my husband is rather fond of Excel!) and I pay attention to those Creighton-ish physical symptoms. (Just the ovulatory ones though. I don't chart every single day, I just pay attention.)
Now I am honestly not sure what an NFP expert would say to do if you're currently breastfeeding (thus having no cycle to track). Nothing except for across-the-board abstinence (or a hysterectomy) prevents pregnancy 100% of the time, so it's always possible that you'll wind up pregnant when you least expect it. Jennifer Fulwiler talked a little bit about that here.
At the end of the day, NFP is a good alternative to hormonal birth control and surgical procedures. It respects womanhood and manhood and does not treat God-given fertility as a disease.
And sometimes you find freedom and beauty in really unexpected or counter-intuitive places. When we made the decision to reject artificial contraception, we discovered the joys of openness to life. Is it always easy? No. But, few worthwhile things are.
Good luck, and thanks for asking!