In re cherrypie’s comment that nfp takes a lot of education and work, I disagree. I would say that there is a lot of investment educationally at the beginning (attending classses), but that as time goes on it requires no further education and vastly decreasing amounts of work. It does not take any more effort than taking the pill did, and it is certainly cheaper and better for your health.
Here is how the STM of nfp really works:
You take your temperature once a day, orally, in the morning before you get up. You can do it vaginally as cherrypie said but I think that would be out of the ordinary. Ideally, your husband is in charge of taking it and writing it down. You have to do it plus/minus 1 hour or so of the same time every day. Nowadays we take it only about 2 weeks of the cycle (to catch the temperature rise—once it’s risen after ovulation there’s no need to take it again until you get your period, although it’s recommended to do so at the beginning so you can get to know your pattern and/or to just be in the habit).
There are rules to adjust the temps if they are at the wrong time or if you are sick with a fever, etc. There are rules for interpreting the rise in your basal body temperature to show that ovulation has come and gone. I have 16 charts so far and every one of them has a temp rise that follows a pattern in my manual, usually the basic pattern. If your temps looked funny (like they can right after discontinuing hormonal bc), you would call your nfp teacher or contact one of many online communities where people can help you out. I’ve never had to do this though.
As for the effort involved in observing cervical mucous (CM), you do this when you go to the bathroom by (this might be Too Much Information, sorry, but you all deserve to know what is really necessary) looking at what is on the toilet paper after you wipe and paying attention to how it feels when you wipe. So if you can bear to think about how it feels and look at that, and maybe touch it to determine its consistency, you can make the CM observation (and then write it down). Some methods use an adjunct internal observation that some women are not comfortable with, but the STM does not. Getting your period is like a hundred thousand million times grosser than the CM observation. Really, it’s not bad or uncomfortable.
At first it might seem a little confusing, but after a month or two it’s like second nature. I would estimate that checking CM takes about 1 to 2 seconds of my time. Additionally, it is not really necessary to make this observation in the post-ovulation (luteal) phase of the cycle (other than to confirm that yes, you are dry with nothing to report for 10-11 days in a row).
The hardest parts of nfp are remembering to write the information down and exercising self-control when you want to avoid getting pregnant but are fertile. For some people this is harder than for others.
Nfp is a commitment you make to one another and I really do think it’s worth it. People who say it’s hard to understand or use the system or that it doesn’t work don’t know what they’re talking about and/or aren’t doing it right (at least for the system I am talking about—there are systems out there that are total junk). Don’t knock it til you learn about it for real and try it.