- Women are not fertile all the time. For the majority of their natural cycles, women are not capable of getting pregnant.
- Women are not fertile forever. It is not unusual for women over 35 have trouble conceiving and by their early 40's many women can't achieve pregnancy. Later pregnancies come with greater risk to the mother and child.
- Breastfeeding reduces fertility, especially if it is ecological breastfeeding.
NaturalGuy and I both knew these facts long before studying and using NFP, because they were at least touched on by our high school sex ed classes. #2 and #3 are considered to be such "matter of fact" biological human quirks that my family wouldn't consider it at all weird to mention it conversationally. And yet, some of our friends are surprised to learn these well into their 20's.
Why are any of these surprising? I suspect that part of the problem is sex-ed classes in schools. Perhaps sex-ed in Catholic schools is more focused on the biology of reproduction? Or maybe it's because our parents wanted grandchildren and never hesitated to tell us to have kids earlier rather than later?
I suspect that a large part of the reason many friends did not know #1 is that their sex education came from a very baby-negative perspective. Teaching students that women are fertile all the time is a way to encourage students to use contraceptives. (Whereas, teaching students at a Catholic school that women aren't always fertile is a way to encourage NFP later.)
#2 isn't taught because it's seen as pressuring women into having children "young." Men, after all, can father children into old age, so it seems inequitable to encourage women who want biological children to try to have their first by age 30 when fertility starts to decline dramatically.
#3 probably stems from our discomfort with breastfeeding. Everyone has a story about a woman who breastfed and had Irish twins (never mind that she was formula feeding as well!).
These misconceptions explain why not using contraception is seen as shocking - and probably a way to have 18+ kids Dugger-style. When Travis and I do the math on how many kids a couple with 30 years of fertility could have, we come to around 15 kids, max. Discussing this with our friends, they were convinced that most couples would have 30 - because they assumed that without contraception, couples would get pregnant every 12 months. If this was the case, I would be terrified to not use contraception too!
I can't imagine trying to "family plan" if this was what I knew about fertility. I imagine it leads to great heartache when couples learn that getting pregnant isn't as easy as they expected.