I’ll name a few reasons that come to mind why people don’t use NFP…
- They can’t have sex whenever they want
- They feel it’s too much “work”
- They don’t realize or believe ABC is against the Church
My mom was blown away when I told her my fiance and I were not only saving the marital act for our marriage (how ironic

but that we were attending NFP classes as part of our pre-cana. She was really impressed with John (my fiance) because my mom and dad started out using the rhythm method (NFP for the 60’s

, but the impression I got from my mom was that my dad didn’t have the “patience,” for lack of a better word.
The second reason is because first you have to learn the Sympto-Thermal Method and then apply it to your daily routine. A woman needs to keep a daily record of her basal body (waking) temperature, internal and external fertile signs, and coitus acts. This can be a pain, especially if she doesn’t have the support of her husband. As JoaoMachado said, when a couple uses NFP and is in it together the effects are astonishing!
I can’t explain the third reason, only to say everyone is on their own faith journey. I used to be an ABC user (not to mention pro-choice

) in my teens and early 20’s and have since done a 180 in my beliefs - Thank God!
As far as NFP’s effectiveness, the numbers change depending on how well the couple is following the rules. Since every woman’s body is different - she may have stronger or weaker signs, longer or shorter monthly cycles, or the couple may decide their desire for each other out-weighs their desire to postpone children

The use of NFP is supposed to be a prayerful one. My husband and I practiced NFP to postpone pregnancy the first 9 months of our marriage because I did not get added to his employer’s insurance policy in the 30-day window after our wedding, but as soon as January 1 open enrollment rolled around we weren’t as careful and by the end of the month, voila!, Beatrice Rosemary was on her way

So even though people tend to think of NFP as primarily for the postponement of children, it’s highly effective in the procreation of children, as well!
Love and God bless,
Bea’s Mom